See Effect of school-based physical activity interventions on body mass index in children: a meta-analysis.
"Meta-analysis showed that BMI did not improve with physical activity interventions (weighted mean difference -0.05 kg/m2, 95% confidence interval -0.19 to 0.10). We found no consistent changes in other measures of body composition."
Some people believe that if going to the gym isn't making them lose weight, they're not exercising hard enough. Chronically over-exercising can chronically raise serum cortisol, which makes the kidneys retain water, causing a stall in weight-loss, as well as causing raised fasting blood glucose, irritability, poor memory and a slower metabolic rate, due to the reduced conversion of thyroxine into tri-iodothyronine.
A healthy body weight is made in the kitchen, not the gym. Buy produce, cook it and eat it!
Although I totally support the use of low-carbohydrate/calorie diets for people with insulin resistance or Type 2 diabetes, now that I'm no longer insulin resistant, I can eat natural carbohydrates, without any problems.
A medium-sized (orange-fleshed) Sweet Potato takes only 4 minutes to bake in its jacket in a 700W microwave oven. The flesh is moist & sweet, unlike that of a Yam or potato.
I eat the whole thing, including the jacket. It's very filling and I'm still able to lose weight. For active and insulin sensitive people, a Kitavan-style diet is absolutely fine.