Is physical activity in weight management more about ‘calories in’ than ‘calories out’?

Abstract

)In the field of obesity research, physical activity has traditionally been considered a strategy to use energy. Most treadmills and exercise bikes display 'calories' and many people are obsessed about burning those extra 'calories', often only to eat or drink them right back. Although the results of exercise programmes designed to reduce body weight are generally considered disappointing, there is no doubt that some individuals can experience substantial weight loss with regular physical activity. In recent intervention studies, the same amount of supervised aerobic exercise has been shown to result in substantial weight loss in some individuals and even weight gain in others (1,2) . Thus, there appears to be almost no relationship between the amount of energy expended during exercise and changes in body weight. For example, a 10 lb (4·5 kg) weight loss within 10 weeks of taking up an exercise programme would require the burning of 35 000 kcal (146 440 kJ), which would correspond to about 1 h of intensive aerobic exercise daily. However, as recently reviewed (1) , physical activity is more than simply a strategy to use energy. The stimulus of exercise provides a wide range of metabolic adaptations that improve overall health and can be associated with marked reductions in abdominal fat and increases in skeletal muscle mass (3) . In addition to the positive effects of exercise on energy expenditure and metabolism, the discussion about the benefits of exercise on weight management generally fails to acknowledge the substantial positive impact that physical activity can have on ingestive behaviour. We hypothesise that while the homeostatic system of energy regulation may well respond with a compensatory increase in hunger (4) , the effects of exercise on the hedonic system can lead to a substantial decrease in energy intake in some individuals. Our hypothesis is based on the evidence that numerous psychological and hedonic drivers of ingestive behaviour can potentially be positively modulated by physical activity. In particular, the regular practice of physical activity has been shown to decrease the risk of stress-induced weight gain (1,5) . Psychological benefits provided by exercise are not trivial and there is no doubt that we should aim at increasing the physical:mental activity ratio in our modern way of living (6) . Additionally, physical activity has been reported to improve sleep quality (7) . Considering that lack of sleep is itself a stressor that has been associated with weight gain (8) , physical activity can have a stress-buffer effect and might improve appetite control in short-duration sleepers. Given that contemporary society is generally characterised by high levels of mental stress and impaired sleep (9) , regular physical activity might help buffering these stressors and breaking the stress-feeding habits. This concept is supported by studies showing that stress-relief activities (e.g. relaxation, yoga, meditation, etc.), which do not burn a large amount of energy per se, are generally effectiv...

Body fat loss and compensatory mechanisms in response to different doses of aerobic exercise—a randomized controlled trial in overweight sedentary males

“…The resulting weight loss in the present trial comprised exclusively of fat mass, demonstrating that even a modest exercise-induced weight loss can be a meaningful "healthy" weight loss (11,47). Current guidelines for physical activity varies somewhat between countries, but in the adult population, ϳ150 min of physical activity per week (54, 59) or 30 min/day (44) is generally recommended to benefit health, while higher doses of physical activity are often recommended to obtain weight loss or to prevent weight gain (27).…”

Energy balance, body composition, sedentariness and appetite regulation: pathways to obesity

“…Interestingly, the idea that physical inactivity could compromise appetite regulation was recognized by Henry Taylor in the 1970s, who related the homeostatic control of appetite to the physical activity performed: It has been proposed that the ability to detect over-or-under-consumption is improved at higher levels of habitual physical activity, with a stronger coupling between energy intake and energy expenditure seen in those with higher total daily energy expenditures (120). Indeed, some have suggested that the primary rationale for promoting physical activity may not relate to the increased energy expenditure associated with such activity, but the effect physical activity has on the sensitivity of appetite regulation (121). Cross-sectional studies have shown that habitually active individuals are able to better compensate for high-energy preloads during subsequent feeding episodes than their sedentary counterparts (122,123).…”

Is the calorie concept a real solution to the obesity epidemic?

“…Hence, it is difficult to agree on which kind of physical activity should be recommended for effective weight control [26]. Whereas some studies and guidelines recommend vigorous physical activity [27,28], other evidence suggests that low-intensity activities such as walking, yoga, meditation and stretching are equally effective in reducing weight [28–30]. Second, energy expenditure might be assessed through technological tools aiming to enhance accuracy, such as pedometers and accelerometers, which measure walked distances and estimate the energy expenditure based on the weight, age and height of an individual.…”