Low Fat vs Low Carb
A study published in August by the National Institute of Diabetes and Digestive and Kidney Diseases (part of the National Institutes of Health) in the journal Cell Metabolism states that when low fat vs low carb diets were compared, a low fat diet led to faster body fat loss by 68 percent.
Carb restriction, however, lowered production of the fat-regulating hormone insulin, whereas fat restriction had no observed changes in insulin production.
“Compared to the reduced-fat diet, the reduced-carb diet was particularly effective at lowering insulin secretion and increasing fat burning, resulting in significant body fat loss,” said Kevin Hall, Ph.D., NIDDK senior investigator and lead study author. “But interestingly, study participants lost even more body fat during the fat-restricted diet, as it resulted in a greater imbalance between the fat eaten and fat burned. These findings counter the theory that body fat loss necessarily requires decreasing insulin, thereby increasing the release of stored fat from fat tissue and increasing the amount of fat burned by the body.”
In the study, 19 non-diabetic men and women with obesity stayed in the Metabolic Clinical Research Unit at the NIH Clinical Center in Bethesda, Maryland for two extended 24-hour-a-day visits, eating the same food and doing the same activities. For the first five days of each visit they ate a baseline balanced diet. Then for six days, they were fed diets containing 30 percent fewer calories, achieved by cutting either only total carbs or total fat from the baseline diet, while eating the same amount of protein. They switched diets during the second visit.
Body fat predictions that the researchers had previously simulated matched the data later collected in the study. The statistical model predicted relatively small differences in body fat loss between the low-carb and high-carb diets, suggesting the body may eventually minimize differences in body fat loss when diets have the same number of calories. Researchers stated that more study should be done to assess the physiological effects of low fat vs low carb over longer periods of time.
“This NIH study provides invaluable evidence on how different types of calories affect metabolism and body composition,” said NIDDK Director Griffin P. Rodgers, M.D. “The more we learn about the complicated topic of weight loss, the better we can find ways to help people manage their health.”
“Our data tell us that when it comes to body fat loss, not all diet calories are exactly equal,” Hall said. “But the real world is more complicated than a research lab, and if you have obesity and want to lose weight, it may be more important to consider which type of diet you’ll be most likely to stick to over time.”
My note: Carb-restricted diets regulate insulin production and generally keep blood sugar levels more stable than most low-fat diets would. Despite these study’s findings, a carb-restricted diet may be a more practical solution to weight loss because of the feelings of satiety that it provides. As the researcher stated, it’s all about finding a diet that you’re able to stick to in the long-term. It’s about making a lifestyle change that you can stick with, not just doing a temporary crash diet for fast weight loss. I also cannot stress the importance of fiber, no matter what diet you’re on. My one diet rule: vegetables. Lots of them. With every meal. I’ll be talking more about this in the weeks to come.