One of the trendiest and most talked-about dieting methods today is intermittent fasting, also called time-restricted eating. In a nutshell, it involves limiting the hours during which you eat each day [for instance, eating all meals and snacks over an eight-hour period and fasting for the remaining 16], restricting calorie intake to about 500 calories per day on certain days of the week, or fasting completely for periods of a day or longer weekly.
The premise behind this trend is based on several effects, shown in human and animal studies, of fasting on the body, which include:
• reduced levels of insulin, making it easier for the body to use stored fat for energy;
• lowered blood pressure and inflammation levels; and
• increased levels of human growth hormone [HGH], which helps the body to more effectively burn fat and build muscle.
Although a number of small studies show that intermittent fasting helps people lose significant amounts of weight and body fat in the short term, research on its long-term effectiveness is both more scarce and more mixed.
For example, one study published in the Journal of the American Medical Association found that over a one-year period, people who fasted on alternate days and those who simply restricted their daily calories by 20% lost virtually the same amount of weight. Other research has found that while amounts of weight lost using the two methods are similar, people who fast see a greater reduction in body fat over time, as well as a reduction in appetite that helps them keep the weight off.
Recently, German scientists also compared intermittent fasting with traditional calorie restriction in a group of 150 overweight and obese people over the course of one year. The researchers found that improvements in those individuals’ health status were similar with both dietary methods, including comparable loss of body weight, belly fat and extra fat stored in the liver. Although they warned that there is not enough data available to determine the safety of intermittent fasting over the long term, they concluded that both methods, when followed strictly, can help people lose unhealthy weight.