In this country, we struggle with obesity. The centers for Disease Control and Prevention (CDC) reported in 2014 that approximately 70.7% of the U.S. population was overweight or obese.
Many adults feel they’ve spent their entire lives dieting, trying one popular diet after another with limited degrees of success. So you might think that your primary care physicians at The Medical Group of South Florida are being a bit cruel to even mention the regimen known as calorie restriction to improve your overall health. While not an easy path, studies suggest the benefits can be profound, even life changing.
Calorie restriction is the process of reducing food intake, usually by at least 30% less than a normal diet. According to the National Institutes of Health (NIH), this regimen has been known since the 1930s to produce numerous health benefits.
For example, a 2016 study performed over two years on adults who were not obese compared those who consumed a normal diet with those who stuck to a 25% calorie reduction. As reported in the online Journal of the American Medical Association (JAMA), the clinical trial conducted at three academic research institutions on 220 men and women found that the calorie-restricted group lost 16 pounds more than the control group. This alone would produce the typical benefits seen with weight loss, including lower risk of Type 2 diabetes, less back and joint pain, and improved cardiovascular health.
In addition, however, the lower-calorie group also reported significant improvement in mood, overall tension, quality of life, sleep, and sexual function. Another study published in the January 2011 issue of Experimental Gerontology reported that rhesus monkeys on a restricted-calorie diet preserved muscle mass during early-stage sarcopenia (aging-related loss of muscle tissue) and averted the normal shrinking of muscle fibers that typically occur with aging. Finally, a report in the September 2012 issue of Nature showed that mice on such a diet outlived control mice by as long as 40 years. These latter benefits might be worth consideration, when measured against the difficulty of maintaining such a restricted food intake.
Because, make no mistake, a calorie-restricted diet is not easy to maintain in our modern culture, where restaurants and fast-food eateries line our streets, where cooking shows proliferate, in a culture in which food often equals celebration, comfort, and camaraderie. Beyond having to overcome such constant temptation, many study subjects have reported frequent hunger, leading to the obvious question, is a calorie-restricted diet worth the difficulty of sticking to it? We are, after all, talking about a diet in the neighborhood of 800 calories a day.
Well, good news may be on the horizon. A new study reported in Scientific American this year from the University of Southern California suggests that many of the benefits—particularly the anti-aging effects—of the calorie-restricted diet can be seen in what researchers termed a “fasting-mimicking diet” which can be practiced just five days a month for three months, and repeated at various intervals as needed. They reported that such a regimen is “safe, feasible, and effective in reducing risk factors for aging and age-related diseases.”
“Safe” the the key word, because severe calorie restriction without careful monitoring for proper nutrition intake can also lead to malnutrition. A famous study during World War II found the many positive metabolic benefits of extreme calorie restriction were outweighed by a host of such negative effects as anemia, weakness, dizziness, and depression, among others, when subjects were not receiving additional nutrients.
Thus, despite the many apparent benefits of severe calorie restriction, it is crucial that you consult with your physician at The Medical Group of South Florida before embarking on any such extreme diet.