Category Archives: weight managment

Do you eat before or after your run?

Many long distance runners perform at least some of their long runs in a fasted state (for example before breakfast, without taking anything), hoping that this will teach their bodies to become more effective at using fats for energy production. Even though it is not sure that it helps on race day, studies have shown indeed that you become better at burning fats if you train your body to do so.

© Mikhail Shifrin | Dreamstime Stock Photos
© Mikhail Shifrin | Dreamstime Stock Photos

The next question is then: would it help you to lose weight? In other words: would you lose more fatty tissue when you exercise in a fasted state than after a meal? Brad Schoenfeld and his colleagues have investigated this and concluded that it does not seem to make a difference. They published their study in the Journal of the International Society of Sports Nutrition in November 2014.

They divided 24 young female volunteers in two groups. One group exercised in a fasted state and the other after consuming a meal replacement shake. They all worked out on a treadmill three times a week at 70% of their maximal heart rate and followed the same diet with the aim to slim down. The women who started by exercising had their shake immediately after the workout.

After four weeks, all the women had lost weight, but there were no differences between the groups concerning amount of weight lost, waist line, lean or fat mass.

The researchers therefore concluded that it does not matter whether you exercise before or after a meal.

Schoenfeld explains the findings by citing previous research showing that our bodies change what they use as fuel, depending on what is available. If you burn more fats for a while, you will use more carbohydrates later in the day, and you have therefore to look at much longer periods than just a few hours.

You might understand their findings better if you think about the First Law of Thermodynamics, which states that energy does not get destroyed or created, but only changes from one form into another. What matter is therefore to get rid of the excess energy, whatever the form it is in.

A study with a negative result?

It is true that reading a study with a negative result is always slightly disappointing, and that is why in the past they did not get published. It is great that this now changing, because it might avoid repeating the same studies over and over again and it might also help us (I hope!) to avoid doing useless things.

Disclaimer: this article is for general information only, and does not replace medical or coaching advice. It cannot be used to guide treatment or training. If you have any concerns or questions, you should talk to a qualified health provider.

References:

Schoenfeld B J, Aragon A A, Wilborn C D et al. Body composition changes associated with fasted versus non-fasted aerobic exercise. J Int Soc Sports Nutr. 2014; 11 (1):54.

Spriet L L. New insights into the interaction of carbohydrate and fat metabolism during exercise. Sports Med. 2014; 44( Suppl 1): 87.

Stannard S R. Ramadan and its effect on fuel selection during exercise and following exercise training. Asian J Sports Med. 2011; 2(3):127.

Van Proeyen K, Szlufcik K, Nielens H et al. Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol (1985). 2011; 110(1):236.

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Could exercising make you eat more?

Many people exercise in order to lose weight or to keep it under control, but does this make sense? It is beyond doubt that regular exercise will improve your health and well-being, but could it make you hungrier, and therefore make you eat more? If so, it would not make any difference for your waistline…

© Andre Maritz | Dreamstime Stock Photos
© Andre Maritz | Dreamstime Stock Photos

In the November 2014 issue of Nutrients, Stephanie Howe and her colleagues published a review article discussing what we know today about this subject. There are still plenty of questions left, especially concerning women, as most studies have been done on men. Studies on women are indeed much more difficult to conduct since oestrogen influences appetite, and researchers therefore have to control for the menstrual status.

Stephanie Howe and her colleagues explain how hormones influence our appetite, and how exercise influences these hormones. They then discuss several studies which have investigated this problem, and finally they look at the impact of diet.

They come to the conclusion that if you are sedentary, an acute bout of exercise is likely to make you overeat. However, as you become well-trained, your body becomes better and better at matching your energy intake with your expenditure.

They also note that as intense exercise suppresses your appetite more, you have to pay attention to what you are having after hard workouts: you could be tempted to eat too little or too late, which will delay your recovery.

Their article is free for all to read, and I will just try to make a summary in lay terms.

What determines your appetite?

Appetite is very complex and influenced by a long list of factors, such as gastric motility, the status of your energy reserves, temperature, dehydration… Your brain receives all this information via hormonal and neural signals, integrates them and then stimulates or suppresses your appetite.

The involved hormones can roughly be divided into two types: tonic circulating and episodic hormones.

The tonic circulating ones reflect your energy reserves and suppress your appetite when your energy stores are full, and are thus more involved with long term regulation. The best known ones are insulin and leptin.

The episodic hormones on the other hand are involved in short term appetite. Most of them are gut hormones and are released when you are eating or just before a meal. They suppress appetite, except for ghrelin, which makes you feel hungry. As their levels depend on what you are eating, it is easy to see why some diets make you feel fuller than others. Foods rich in fibres for example, will allow you to take in fewer calories without feeling hungry.

As mentioned earlier, oestrogen and progestogen also influence appetite, which explains why many women tend to gain weight during the menopause.

All these hormones act on the hypothalamus (an organ in your brain), which integrates the information and controls your appetite. Despite this sophisticated system, other factors, such as the sight and smell of food, cultural and social elements or the time of the day, also influence your desire to eat and can even override the hormonal influences.

Working Up Sweat (ID: 74747)
© Vlad | Dreamstime Stock Photos

Studying appetite

Researchers who want to study the influence of exercise on appetite therefore have to measure the amount of the appetite hormones in your blood as well as your desire to eat. The first can easily be done by a blood test, and the latter is often done using a visual analogue scale (VAS) or by measuring what the participants eat at a buffet in the research centre. A visual analogue scale typically consists of a series of numbered boxes (e.g. from 1 to 10), where the first and the last ones correspond to the extremes (e.g. “I’ve never been so hungry” and “I couldn’t eat anything at all”). You can then mark the box that corresponds best with how you are feeling.

Appetite hormones and exercise

A bout of aerobic exercise decreases your appetite by influencing your gut hormones. This effect is more pronounced in weight baring and more metabolic demanding exercise, such as running, than in non weight baring exercise.

Intense exercise influences the hormones more than moderate exercise. This suppression is only temporarily, but it can be enough to interfere with your next meal, and therefore with your recovery. This explains why it is so hard to eat anything solid after a race!

Resistance exercise on the other hand, does not seem to have an influence.

Are you really eating less?

It is not because your hormones are suppressing your appetite that you will eat less. As I am sure you know by experience, you can override your appetite if the food looks nice or if you believe you have good reasons to eat (e.g. I have spent a lot of calories, I need some comfort after all this hard work…).

© Ragne Kabanova | Dreamstime Stock Photos
© Ragne Kabanova | Dreamstime Stock Photos

Most studies looking into energy intake after exercise do so by measuring what the participants eat at a buffet offered by the researchers. This does not necessarily simulate real life and might therefore lead to false conclusions. Even so, there is evidence that trained people are able to match their energy intake to what they have spent, and can therefore maintain a healthy weight. Sedentary people however, are more likely to overeat after an acute bout of exercise.

Diet

Most athletes are health conscious and will choose a diet rich in fruit, vegetables, whole grains etc…Such a diet will contain fewer calories per volume than an unhealthy one. It will also make you feel full much earlier. For the vast majority of us this is excellent news, but the combination of a low calorie diet, intense exercise and appetite suppression can become a trap for some athletes. It can lead to a chronic negative energy balance, and is more often seen in women engaged in sports for which being lean is an advantage, such as long distance running. It can lead to menstrual disorders with all their complications: poor bone health, injury, illness…

Recovery

If you want to recover quickly, you have to refuel as soon as you can. This can be difficult if your appetite is suppressed. Other factors such as fatigue, dehydration, an elevated core body temperature or gastrointestinal problems can make things even trickier. A good recovery drink can help you out though, as drinking is much easier than eating.

 

Sleep enough to keep slim

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© Peter Elvidge | Dreamstime Stock Photos
© Peter Elvidge | Dreamstime Stock Photos

 More and more people are overweight or obese and at the same time more and more people do not sleep enough. Could there be a link? Scientists have studied this problem by asking participants to reduce their sleep, usually from 8.5h/day to 5.5 h/day. They then noted what and how much the participants ate, and measured any hormone or body weight changes. Most of them would now answer yes indeed, there is a link.

It is clear that nobody believes that you can sleep excess weight off, but not sleeping enough (less than 7 hours/day) can hamper your efforts to slim down or keep your weight under control.

At a first glance this looks unbelievable, as when you are awake for longer, you are going to spend more energy.

The energy you spend consists of 3 components:

1) what you need to keep your body going (your basic metabolic rate),

2) the amount needed to assimilate food,

3) the energy used for all kinds of exercise and activities.

When asleep, you will not eat or move and your basic metabolic rate is reduced by 20-30%. Scientists have calculated that sleeping 5.3h instead of 8h would increase the amount of energy you spend by 45 kcal/d.

However, it is here that your unconscious brain starts interfering. As we have seen in some previous posts (e.g. here or here), your brain wants to keep you safe and it therefore wants your energy balance to remain the same. The balance between the energy you take in and the energy you spend determines your body weight, and depends on genetic, psychological and behavioural factors. Even if it sets your body weight a bit too high for your health, your brain will be unwilling to change it, as anybody who has ever tried to lose weight knows only too well.

Experiments have shown that when you have not slept enough, your brain will stimulate you to eat more to compensate for the energy you have spent. Unfortunately, it will make you overdo it. It will do so by making food more rewarding, and the data show that you will tend to snack more and to choose more fatty and carbohydrate-rich food. This is easily done in our modern world where food is widely available.

© Remigiusz Oprzadek | Dreamstime Stock Photos
© Remigiusz Oprzadek | Dreamstime Stock Photos

It is easy to see how all this will put your best efforts to stay slim in jeopardy. Moreover, a study by Arlet Nedeltcheva showed that dieters who slept for only 5.5 h/day lost more lean body mass and less fat than dieters who slept for 8.5h. They also suffered more from hunger.

Researchers have also studied the effect of insufficient sleep on next day’s activities. Even though some of them have not observed any effect, most report more sedentary time and less vigorous workouts. The discrepancy might be due to the fact that some study participants were used to insufficient sleep, or to the short duration of some studies which could not capture the full effect on people who exercise a few times a week.

There are still plenty of questions to be answered, e.g. what is the effect of habit, is there a difference between men and women, is what scientists observe in a study the same as what happens in real life etc…We do not know either what the effect of physical exercise is: regular exercise improves your sleep, which would then influence your energy balance. Nevertheless, it is a good idea to make sure you have enough sleep!

 

References

JP Chaput and MP St-Onge. Increased food intake by insufficient sleep in humans: are we jumping the gun on the hormonal explanation? Front Endocrinol (Lausanne). 2014; Jul 15;5:116. doi: 10.3389/fendo.2014.00116. eCollection 2014 (accessed 26/08/2014).

A V Nedeltcheva, J M Kilkus J Imperial et al. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010; 153(7): 435-441.

P D Penev. Update on energy homeostasis and insufficient sleep. J Clin Endocrinol. Metab. 2012; 97(6): 1792-1801.

MP St-Onge. The role of sleep duration in the regulation of energy balance: effects on energy intakes and expenditure. J Clin Sleep Med. 2013; 9(1): 73-80.

Do we snack because we are bored?

Several studies have shown that television watching makes you snack more, which is very dangerous for your waistline, while others have found no effect. Could this discrepancy be due to the content of the programmes? If so, choosing your programs wisely would help you to keep your weight under control.

© Kmitu | Dreamstime Stock Photos
© Kmitu | Dreamstime Stock Photos

It is possible that your mood, in particular your level of boredom, could influence how much you are eating. To check this out, Colin Chapman and his colleagues compared how much 18 normal-weight women snacked when watching an engaging comedy program, with what they ate looking at a boring lecture or reading a boring text. The snacks consisted of grapes and M&M chocolates.

The women snacked significantly less during the engaging television program than during the boring one or while reading the boring text. There was no real difference between the amount snacked while reading or watching something boring.

Previous studies have already shown that obese people tend to eat more when bored, but now more and more researchers think that everybody does so. Moreover, if Colin Chapman is right it would mean that being bored by other means than television watching (in this experiment: reading) is just as bad.

The researchers also noted that when bored the women snacked more on grapes than on chocolates. When captivated however, they had relatively more chocolate. They suppose that when the women had more time to choose, they went for the healthy option. Even so, they took in more calories than when they were captivated.

Of course, this experiment was conducted in a lab and the women might behave otherwise when at home. The researchers did not check what the women ate after the experiment and we therefore do not know if there was any effect on the size of their meal.

We do not know either what the women were used to do. Habits are powerful, and if you are used to snack while watching television or if you associate snacking with having a good time, you will find it harder to control it.

Even so, if you want to keep your snacking under control, you should avoid boring stuff… Alternatively, you could make sure that there are no snacks available when you have boring things to do, which is probably a more realistic solution.

References

CD Chapman, VC Nilsson, HA Thune et al. Watching TV and food intake: the role of content. PLoSOne. 2014; 9(7): e100602. doi: 10.1371/journal.pone.0100602. eCollection 2014.

Choose chewier food to eat less

A mounting amount of evidence shows that eating with smaller bites and keeping your food for longer in your mouth makes you take in fewer calories. However, as all these studies have been done under standardised conditions in labs, it is not clear how you could do this in daily life. How can you keep taking smaller bites and keeping food in your mouth for longer while chatting or watching television?

© Max Blain | Dreamstime Stock Photos
© Max Blain | Dreamstime Stock Photos

In her latest article on the subject, Dieuwerke Bolhuis suggests choosing harder foods, which will need more chewing, to achieve just that without having to think about it.

Bolhuis and her colleagues asked 50 volunteers to have a meal of harder foods and one of softer foods for lunch on two different days. The volunteers ate as much as needed to feel “pleasantly full” while the researchers filmed them to determine their bite size and the time it took them to chew and swallow the food. The volunteers were invited for dinner on the same day as they had lunch. They could again eat as much as needed, and the researchers calculated the amount of energy they were taking in.

Eating harder foods indeed forced the volunteers to take smaller bites and chew longer, and led to a 13% lower energy intake. They did not compensate for this at dinner, which means that had eaten substantially less over the day without noticing any difference.

Click here to see the results as a graph: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3973680/figure/pone-0093370-g002/

If you could keep having about 13% less energy a day, you would quickly lose weight indeed. Moreover, the harder or chewier foods are often the healthier ones as well, as they are likely to be less processed or to contain more fibre. Unfortunately we do not know yet whether this can go on day after day: would your body end up compensating by eating more?

Anyway, it is certainly something to try out.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References:

DP Bolhuis, CG Forde, Y Cheng et al. Slow food: sustained impact of harder foods on the reduction in energy intake over the course of the day. PloS One 2014; 9(4): e 93379. doi: 10.1371

Why do so many diets fail?

Weight and height are used in computing body m...

The vast majority of dieters regain weight as soon as they try to eat normally again. Do not blame yourself if this is your case, as your body cannot make the difference between dieting and starvation. When you start dieting, it therefore “thinks” that there is not enough food available, and it tries to conserve energy. Consequently, you will regain weight as soon as you are eating slightly more.

In February 2014, Eric Trexler and colleagues reviewed what we know about the changes in our bodies due to weight loss. They looked at it from the point of view of athletes, as many of them want to lose weight –or at least keep it under control. Long distance runners for example, want to keep their body fat percentage low. However, the mechanism is the same for everybody.

Weight loss and your hormones

A number of hormones, such as thyroid hormone, leptin and ghrelin, are important for the regulation of energy expenditure and intake. They act together to maintain the body weight you use to have, even if it is too high, by regulating the amount of energy you spend and your appetite. If you want to lose weight and keep it off, you will have to resist this mechanism.

The energy you are using

Your total energy expenditure includes your resting energy expenditure (energy needed to fuel the minimal requirements of your body at rest), your activity related energy expenditure and the energy you need to digest food.

Your resting energy expenditure is usually about 60% of your total expenditure. As you lose weight however, it decreases, which can thus lead to weight regain or to difficulties in further slimming down.

Your activity related energy expenditure also declines, as you will burn less energy to run or walk when you are lighter. Moreover, experts believe that your body becomes more efficient, which means again that you are burning less calories for the same workout.

Finally, as you are eating less, you need less energy to digest your food.

Your appetite

Your hormones will also increase your appetite. As if that is not enough, there is good evidence that they will stimulate you to eat food high in sugar and fat. On the other hand, high-protein, low-glycemic index diets are better to prevent weight regain, as they tend to make you less hungry.

What can I do?

You will have to watch what you eat well after the cessation of your diet. You might therefore want continuous support and advice.

It is likely that all these effects are proportional to the energy deficit. In other words: the fewer calories you take in, the more energy your body tries to conserve. If you reduce your food slowly and gradually, your body’s adaptations will be much less important.

Some people practice “refeeding”, whereby they eat more than required for a day or so in order to maintain their resting energy expenditure. However, we need more research to know it this is beneficial.

If you want to regain weight after dieting, you should increase the amount of calories very slowly. Studies have shown indeed that a rapid weight gain is usually only due to an increase in fat mass, while it is likely that you would like to increase your muscle mass.

References:

Eric T Trexler, Abbie S Smith-Ryan and Layne E Norton. Metabolic adaptation to weight loss: implications for the athlete. J Int Soc Sports Nut. 2014; 11:7.

Erik S Blomain, Dare A Dirhan, Michael A Valentino et al. Mechanisms of weight regain following weight loss. ISRN Obes. 2013; 2013: 210524.

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What is the best exercise to get back in shape?

Exercise is a well established tool to keep healthy. The American College of Sports Medicine recommends a minimum of 150 min endurance exercise a week and 20 min of resistance exercise two to three times a week (click here for more details).This is only a minimum indeed and if you are reading this, it is likely that you want to do more to improve your health further. Whatever your goals are, it is important to determine which kind of exercise is the most effective, as we are all short of time.

Cyber Soldier shows prowess in endurance events

Several researchers have studied how and if endurance training, resistance exercise or a combination of both affect health parameters such as body weight, waist circumference, lean body mass, blood lipids, fitness… Lukas Schwingshackl and his colleagues have reviewed these studies to determine which modality would be the most effective, and in December 2013 they published their conclusions in PLoSONE.

Results

The main result was that endurance exercise was the most effective to reduce body weight, waist circumference and fat mass, and to improve fitness (as measured by VO2max). Resistance exercise however, was better to increase lean body mass. There were no significant differences in the improvement of the blood lipids between the exercise modalities.

Researchers use waist circumference to estimate visceral fat, which is an important risk factor for cardiovascular disease. A reduction in waist circumference, suggesting a decrease in visceral fat, is thus an important result. An increase in VO2max is associated with reduced all-cause mortality and a lower risk of cardiovascular risk. Endurance training can thus really improve your life!

Resistance training leads to an increase in lean body mass, thus in muscle mass and strength. This counteracts the loss you normally experience due to aging. This is important, as the tasks of daily life do not become lighter because you are getting older. If you want to stay active and independent in old age you have to maintain your strength.

English: Participant being guided through resi...

Lukas Schwingshackl and his colleagues concluded from their review that combining endurance with resistance training allows us to reap the benefits of both modalities, and is therefore the most promising regimen. However, they admit that this increases the time you spend exercising. In two of the reports they examined, the time even doubled.

If you don’t have time

In 2011, Criz Slentz compared the effects of endurance training, resistance exercise and a combination of both on 249 volunteers, taking great care that everybody was spending the same amount of calories while exercising. He also concluded that endurance training was more effective than resistance exercise to reduce visceral fat and to improve fitness, but he could not notice a difference between the effects of endurance and combination endurance/resistance training. As resistance training is more time consuming, he advised to keep to endurance training.

Can I believe the review?

Lukas Schwingshackl’s review is a meta-analysis, which means that they analysed, evaluated and compared studies done by other researchers in order to come to a conclusion. This saves people like you and me a lot of time and effort!

On the other hand, we have to trust that they have excluded all the bad studies and kept the good ones. In theory, there is always a danger that reviewers cherry-pick the studies they like.

Moreover, reviewers can only analyse studies that have been published. As nobody likes to read negative results or no-reports, only the positive ones get published. It is therefore always possible that a review is biased because of a lack of data. This is called publication bias and is very hard to avoid.

What does it mean for me?

As yet, we can conclude that a training regimen combining endurance and resistance exercise is the best option. If you are short of time however, you should stick to endurance training.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.

References:

Schwingshackl L, Dias S, Strasser B et al. Impact of Different Training Modalities on Anthropometric and Metabolic Characteristics in Overweight/Obese Subjects: A Systematic Review and Network Meta-Analysis. PLoS ONE. 2013; 8(12): e82853. doi:10.1371/journal.pone.0082853.

Slentz C, Bateman L, Willis L et al. Effects of aerobic vs resistance training on visceral and liver fat stores, liver enzymes, and insulin resistance by HOMA in overweight adults from STRRIDE AT/RT. American Journal of Physiology – Endocrinology and Metabolism. 2011; 301: E1033-E1039. doi: 10.1152/ajpendo.00291.2011.

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Should we eat more nuts?

Small bowl of mixed nuts displaying large nuts...

A large study in BMC Medicine has shown that eating nuts protects against cardiovascular disease and cancer, even if you have a healthy diet. Marta Guasch-Ferre and her colleagues studied 7,216 individuals over 4.8 years, and those who consumed more than 3 servings of nuts a week (one serving = 28g, which is about a handful) had a 39% lower mortality risk.

What is so special about nuts?

Tree nuts have been an important part of our diet since the Stone Age, but their consumption has recently declined in most industrialised countries.

The most popular edible ones include walnuts, hazelnuts, pistachios, pine nuts, brazil nuts, macadamia and almonds. Peanuts are in fact legumes, but as they have a nutritional profile similar to tree nuts, they are considered as such. Chest nuts on the other hand, are different, and even though botanically they are nuts, they are not consider as such here.

Nuts contain a large amount of vegetable protein, fibre and unsaturated fatty acids. They are cholesterol-free and rich in phytosterols. The latter interfere with our cholesterol absorption and can therefore help us to keep our cholesterol levels down.

Nuts are rich in vitamins (such as folic acid, vitamin B6 and E), and many other bioactive substances such as phenols. Their outer soft shell or skin contains most of the antioxidants, and when this pellicle is removed, more than halve of the antioxidants are lost. Blanching also destroys them. It is therefore better to have your nuts raw and unprocessed.

They have an excellent combination of minerals: a small amount of sodium, and plenty of calcium, magnesium and potassium. This will protect you against arterial hypertension and insulin resistance, and therefore against cardiovascular disease. Obviously, if you eat your nuts salted, you will lose these benefits.

Marta Guasch-Ferre and her colleagues have also shown that walnuts help to protect you against cancer. They are richer in polyphenols than other nuts, and as you usually eat them raw and with their skin on, you will also get more antioxidants from them.

Two Juglans regia walnuts.
Two Juglans regia walnuts. (Photo credit: Wikipedia)

Adverse effects of nuts

As they are rich in fat, people tend to avoid them to keep slim. However, studies have demonstrated that regular consumption does not lead to weight gain, and some researchers have even shown that nut-eaters are leaner than the general population. This is probably due to the fact that nuts make you feel full for longer, and as a consequence you will eat less other energy-dense food.

The big problem is that they can trigger a life-threatening allergic reaction. Once the diagnosis of nut allergy is made, the patients and their families should avoid all nut products, which can be challenging as they are often hidden in processed food. If somebody you live with suffers from this condition, you should know exactly how to recognise and treat an allergic reaction.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider

References:

M Guasch-Ferre, M Bullo, M A Martinez-Gonzalez et al. Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial. BMC Medicine 2013; 11:164 doi: doi:10.1186/1741-7015-11-164.

E Ros. Health benefits of nut consumption. Nutrients 2010; 2(7): 652-682

Dangers and Benefits of High-Protein Diets

High-protein diets are very popular, as they help you to lose weight and increase muscle mass. Unfortunately, they can also lead to chronic metabolic acidosis and harm your health, unless you eat plenty of fruit and vegetables.

The classical recommendation is to get 45 to 65% of your calories from carbohydrates, 20 to 35% from fat and 10 to 35% from protein. High-protein diets (16 to 45% of your calories as protein) are very popular with slimmers as they make you lose weight much quicker than traditional diets. Athletes, even recreational ones such as you and I, are tempted to eat more protein to build up their muscular strength. On the other hand, a diet rich in animal protein can result in metabolic acidosis, which is bad for your health.

Tasty Food Abundance in Healthy Europe

In the April 2013 issue of Nutrition Journal, Lukas Schwingshackl and Georg Hoffmann reviewed the studies comparing low-protein with high-protein diets after a 12 month follow-up. They did not find any significant differences in waist circumference, fat mass, serum lipids (e.g. cholesterol), blood pressure or insulin levels. They concluded that as high-protein diets did not offer any advantages and could be dangerous, there are no reasons to adopt them.

Dr Santesso and colleagues had performed a similar review in 2012. They noticed some small improvements in triglycerides levels, blood pressure and waist circumference, but they wondered if these effects were worthwhile compared to the risks.

This brings us to the crucial question: what are these risks? They are linked to the acid-base balance in your body.

Metabolic acidosis
Your body keeps your acid-base balance under tight control, and your blood plasma pH is therefore stable. Unfortunately, a diet containing a large amount of animal protein is highly acidic. If the amount of acids increases, your body will buffer it with bicarbonate and your kidneys will excrete more acid. Your will bring your pH back to normal, but your bicarbonate levels will be lower and your urine more acid. This new balance is called metabolic acidosis.

However, as everything is linked and works via chain reactions, a new balance is never good news. It does not have any health implications if it happens only occasionally, but if it continues for many years it can lead to chronic disease.
Even though your kidneys have to work hard to keep your acid-base balance right, high-protein diets do not lead to chronic kidney disease. They will aggravate an existing one though, and you should therefore have a chat with your doctor before embarking on such a diet.

Consequences of a lifelong metabolic acidosis
Metabolic acidosis leads to insulin resistance (= when your cells are less responsive to insulin stimulation) and high blood pressure, and puts you therefore at risk of diabetes and cardiovascular diseases. The situation gets worse as you get older, probably because the kidneys become less able to correct the acid-base balance due to aging.

Recently, scientists have discovered that metabolic acidosis stimulates the formation of reactive oxygen species, which can damage cells and lead to cancer.

Calcium and bones
People who have a high-protein diet lose more calcium via the urine. It is not clear yet why, and it is unlikely to be linked to metabolic acidosis. On the other hand, protein stimulates calcium absorption from the intestine, and therefore scientists have wondered for many years how a high-protein diet affects your skeletal health. Most of them now feel that it is beneficial, but the effect is probably not large enough to make a difference in your fracture risk. As yet, they have not been able to show that plant proteins are better than animal ones.

Advantages of a high-protein diet

Losing weight
A high-protein meal makes you quickly feel full and less hungry at the following meal. As a result you will eat less and lose weight.

The energy you need for the digestion, absorption and disposal of food is called the thermic effect. It seems to be larger for protein than for carbohydrates and fat. Scientists agree that the differences are quit small, but taken over a period of time they become significant.

Even if in the long term you will not lose more weight on a high-protein than on low-protein diet, it is always nice to see some results early on!Textured Soy Protein Soup

Muscular strength
An adequate protein supply is essential to maintain or increase your muscle mass. Studies have shown that the combination of ingesting protein and resistance training results in the greatest muscle gain. This is not only important for athletes, but also for elderly people, who need to increase -or at least maintain- their strength to remain independent and avoid falls.

Animal or plant products?
Studies have shown that proteins from plants are often less acidic than those from animal products. Moreover, fruit and vegetables contain alkalising substances, such as potassium and magnesium, which will help buffering the acids.

Click here for lists of fruit and vegetables containing proteins.

What does it mean for me?
You could replace part of your refined carbohydrates by proteins from a source poor in saturated fat, as long as you keep your acid-base balance under control by eating plenty of fruit and vegetables. Consult your doctor first.

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment, or to revise your diet without supervision from a qualified health provider. If you have any concerns or questions, you should talk to your doctor.

Links between visceral fat, exercise and longevity

A public demonstration of aerobic exercises
A public demonstration of aerobic exercises (Photo credit: Wikipedia)

Exercise improves your health and can make you live longer even if you do not lose weight.

In November 2012, a study in Plos Medicine showed that being more physically active is associated with a longer life, whatever your weight is. Physically active people with a normal weight had the best life expectancy, but being active and overweight or mildly obese (BMI up to 34.9 kg/m2) was better than being inactive with a normal weight. The authors concluded that exercise is beneficial for everybody, and doing a small amount is better than nothing.

In an article published earlier this month in Plos One, Dirk Vissers and colleagues reviewed all the studies looking at the effect of exercise without dieting on visceral fat in overweight and obese people. They noted that exercise reduced visceral fat, even in people who did not lose weight. They also showed than moderate or vigorous aerobic exercise was more effective than low intensity or resistance work.

This could well explain why physically active people do better than sedentary ones. In any case it is excellent news for all of us who train hard but do not manage to lose much weight.

Subcutaneous or visceral

Fat tissue affects your health depending on where it is. If you take in more calories than you need, your body can store the excess energy as subcutaneous (just under the skin) or as visceral fat (in and around organs such as the liver or pancreas).

For more than 50 years now, studies have shown that excess visceral fat leads to chronic diseases such as diabetes, cardiovascular disease and metabolic syndrome. Subcutaneous fat on the other hand, does not put you at a higher risk.

Your waist circumference is a better measure of your visceral fat than your body mass index (BMI). To learn how to measure it, click here.

The problem with visceral fat

Visceral fat behaves as an organ and produces molecules, adipokines. We do not know much about adipokines yet, but scientists have noticed that they can act as hormones. When the visceral fat depot enlarges, the adipokine production becomes disturbed, and this puts you at a higher risk of chronic disease.

A large amount of visceral fat becomes easily inflamed, leading to a chronic low-level inflammatory state which increases your risk even further.

Exercise

Dirk Vissers showed that regular physical activity is associated with a reduction in visceral fat, even if there is little or no change in weight. If you are losing fat, especially visceral fat, you are probably gaining lean body mass. The result can be that your weight stays the same, even though your waist circumference decreases. Obviously, if you are losing weight as well as reducing your waist circumference, you are losing even more visceral fat.

An acute bout of exercise does more than just burning calories

During an acute bout of exercise, the blood flow in fatty tissue increases. It therefore gets more oxygen and a larger amount of several hormones, such as cortisol and adrenalin, than when you are less active. This increases fat mobilisation and affects adipokine secretion.

For 24 hours or so after your workout, fat that comes from your diet will be directed to your muscles instead of being stored in adipose tissue, probably to make sure that you have energy available for your next exercise bout. As a result, your blood levels will be lower and your fatty tissue does not enlarge.

After just one session of aerobic exercise insulin sensitivity (= ability of tissues to respond correctly to insulin) increases by 20% in healthy as well in diabetic people. As insulin resistance (the opposite of insulin sensitivity) is linked to chronic disease and diabetes, this is important for your health. It persists for a day or two.

Training

Chronic exercise or training is just a series of acute bouts. If you exercise on a regular basis, for example every other day, the effects of each bout will continue into the next one, and the accumulation will improve your health much more than a diet can ever do.

As fatty tissue gets mobilised on a regular basis, it becomes more responsive. Scientists believe that sedentary obese people have “inflexible” fatty tissue, which resists stimulation by hormones, and they think that training can correct this.

It is obvious that weight management is more than calculating calories. We still have a lot to learn about it.

Further reading:

D Thompson, F Karpe, M Lafontan and K Frayn. Physical activity and exercise in the regulation of human adipose tissue physiology.  Physiol Rev 2012; 92(1): 157-192

Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.