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.
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.
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.
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.