Because of the addictive nature of fatty foods, sugars, and artificial sweeteners (and here), the average body mass index for the general U.S. population is nearing the obesity cut-off, and even children as young as five are now getting bariatric surgery. Obesity metabolically contributes to insulin resistance because of free fatty acid spillover into the blood. Even vegetarians are, on average, overweight in the United States but those eating more strictly plant-based diets average an ideal body weight. Meat has been found to increase the risk of being overweight (here and here), obesity, and obesity related diseases. This may be due, in part, to the consumption of chickens which are themselves obese and may be infected by an obesity-causing virus (and here).
Conversely, plant-based diets may help prevent weight gain, promote weight loss (even insidiously), and maintain desired weight by increasing resting energy expenditure, lowering energy gain, up-regulating metabolism, improving satiety, preventing fat cells from taking up fat, and improving plasma adiponectin levels (a hormone that helps control weight). Ancillary benefits may include less painful periods. Ordinary foods such as oatmeal and beans can produce extraordinary benefits. Our tastes can acclimate to healthy changes, such as substituting cocoa for chocolate (using healthier sources of fat and sugar). You do not need to give up snacks, if you do it right, with nuts and dried fruit.
Healthy food choices can raise your resting metabolic rate and help burn fat with no additional effort. Soy foods may help double weight loss and promote abdominal fat loss while protecting against breast cancer. In addition to consuming a primarily plant-based diet, adding nuts (here) and dates to your diet and drinking green tea on a daily basis may be useful in the prevention of obesity. Eating more slowly will help you feel full on less food. The beneficial gut microflora (and here) established and maintained by a plant diet rich in flavonoids and arginine promote fat loss. Nuts do not appear to lead to the weight gain one might expect given their caloric density (also here, here, and here). Spicy foods may also help activate our brown adipose tissue, facilitating weight loss.
Diet supplements do not seem to work. And, caloric restriction may not protect against cancer as well as a healthy plant-based diet. A paleo diet may undermine the benefits of exercise. The low-carb Atkins diet is associated in greater mortality from all causes, although replacing its animal fats and proteins with plant sources does improve survival in plant-based, low carb diet adherents. Even vigorous exercise may be less important than diet in reducing obesity or slowing cellular aging (the shortening of our telomeres).
Topic summary contributed by Ted.