Scientists from Canada, China and the United States found that popular diets are roughly equally effective to reduce the weight and improve the cardiovascular system, but the effect of each of them lost in a year. For this they conducted a meta-analysis of 121 work with almost 22 thousand participants: weight loss, changes in blood pressure and concentrations of cholesterol for diets differed in the first six months, but a year later, all parameters return to the former. Article published in The BMJ.
The question of which of all the existing diets most effectively still remains — largely due to the fact that when selecting, you need to consider many different factors. For example, to reduce weight the correct way is to monitor the amount of food consumed and the energy that a person spends: weight loss in this case, it provides a caloric deficit. On the other hand, in case of certain metabolic disorders may help, for example, a low-carb diet — even if weight loss is not observed. But when weight loss this diet is not more effective than that which is observed low in fat.
The effectiveness of the diet should be assessed not only in terms of how weight is lost and health is improved during its observance, but as a long time storing the result. This parameter decided to evaluate scientists under the guidance of the Moon GE (Long Ge) from Lanzhou University. For their meta-analysis, they collected 121 study with a total number 21942 participants with overweight or obesity.
Each study used one of the 14 popular diets, divided into three groups: low carbohydrate (e.g. Atkins diet), diets low in fat (e.g., diet Ornish) and balanced diets (e.g., Mediterranean). In each study had a control group — participants who adhered to their usual diet. On average, the duration of the diet in each study was six months, but all works were available information about the health of the participants and a year after the change of power.
In addition to weight changes, the scientists also evaluated the effect of diet on blood pressure, concentration of lipoproteins of high and low density, as well as C-reactive protein in blood plasma, whose concentration increases in inflammation.
Compared with normal diet, low-carbohydrate diets, and diets low in fat for six months led to about the same weight loss (and 4,63 4,37 kg, respectively), and equally effectively reduced blood pressure. Have a balanced diet the effect was slightly less pronounced: the average weight loss was three pounds and diastolic blood pressure decreased by 3.48 millimeters of mercury (compared to five and higher for diets with low carbohydrates or fats). In addition, a diet low in fat was more effective for reducing low-density lipoprotein (so-called “bad” cholesterol).
A year after the beginning of each of the diets, however the weight returned to the figure to start a diet — the same was true for parameters of health of the cardiovascular system. However, if the Mediterranean diet effect on the cardiovascular system was maintained. The authors noted that to achieve the best result, so you need less to focus on choosing diet and pay more attention to how to save the result.
Weight loss and the improvement of the heart and blood vessels — not only the goals pursued by the people who are changing their diet. For example, for the prevention of depression, as revealed by two years ago, the study is well-suited Mediterranean diet.