To combat obesity it is not important how much you eat but what you eat! This is what emerges from two very recent studies published a few days ago, one in The American Journal of Clinical Nutrition by an American team (Ludwig et al, AJCN, 2021) and the other in The Journal of Physiology by a group of Polish scientists (Chrobok et al, J Physiol, 2021).
The problem of obesity
According to statistics, in almost all OECD countries more than half of the population is overweight and one in four is obese. The problem of extra pounds is not aesthetic, but concerns health. In fact, obesity is associated with an increased risk of developing diabetes, cardiovascular disease and even some types of cancer. This is why more and more scientific studies are trying to understand the mechanisms that lead to obesity in order to be able to prevent it effectively. Until now, the main cause of the spread of overweight and obesity was attributed solely to an excessive increase in ingested food associated with poor physical activity. In reality, the situation looks different and opens up very interesting scenarios for more efficient weight management. But let's understand better.
Not how much but what you eat, the problem of excess fat
Both studies have made it possible to observe that what triggers obesity is not how much you eat but what you eat. For example, a high-fat diet disrupts the biological clock in the brain that manages hunger and satiety. It is then this alteration that causes overeating and hence obesity. Until now it was believed that it was only the hypothalamus that regulated appetite. Instead, recent research has shown that other areas of the brain and body are also used to regulate appetite, such as the vagal dorsal complex, which intervenes by inducing satiety. Well, the researchers observed that, in mice, a diet rich in fat is able to alter the vagal dorsal complex and this is already observed in the short term, still in the absence of weight gain. Therefore, it is hypothesized that, in the presence of a high-fat diet, the antechamber for obesity is precisely an alteration of the mechanism that normally intervenes to keep hunger under control.
Whole grains are better
But the problem is not only in a diet rich in fat. In fact, a common mistake that is made is to replace a high-fat diet with a low-fat diet that is high in refined carbohydrates that are absorbed quickly. Well, the researchers observed that ingesting high amounts of refined carbohydrates leads to alterations in the release of hormones that affect the metabolism, causing fat accumulation and an increase in weight and in the risk of developing obesity. In fact, an excess of rapidly absorbed carbohydrates causes a glycemic peak, followed by an increase in insulin and a reduction in glucagon. Thus a perverse mechanism is established. In fact, excess insulin causes blood sugar to drop, giving the body a signal that it is lacking energy, thus inducing a sense of hunger and stimulating the accumulation of fat to nourish the muscles and tissues of the body. Glucagon is a hormone that stimulates the mobilization of fats from adipose tissue, which are then burned for energy. A reduction in glucagon leads to an increase in the accumulation of fat. So, as we gain weight, we feel hungry all the time.
The two researches have made it possible to understand, once again, the importance of a varied and balanced diet, which favors the consumption of unrefined cereals and fiber from fruit and vegetables capable of slowing down the absorption of sugars. In addition, it is good to choose a diet that does not include an excess of fat in order not to alter the complex body mechanisms of metabolism and promote effective control of body weight.