A new study, recently published in the Journal of the American Medical Association, indicates that for those looking to lose weight, the quality of food they eat is more important than the quantity. Conventional wisdom surrounding weight loss has long emphasized the singular importance of calories, without much consideration for the quality of the foods that contain those calories. We’ve always been told that reducing caloric intake is the path to weight loss, leading to a proliferation of highly processed low-fat and “diet” foods with low calories, but poor quality. This study challenges such conventional wisdom about calories, supporting the idea that eating high-quality food is far more important than strictly counting calories.
The study, led by Christopher D. Gardner, the director of nutrition studies at the Stanford Prevention Research Center, followed more than 600 overweight or obese people for a year. Participants in the study received regular instruction from dietitians, encouraging them to cook meals at home whenever possible, and focus on minimally-processed, unrefined, nutrient-dense food. The participants were divided into two groups, one directed to follow a healthy low carb diet, the other directed to follow a healthy low fat diet.
The low carb group was encouraged to eat nutritious low carb foods such as avocados, salmon, nuts and seeds, green vegetables, and grass-fed meat. The low fat group was encouraged to eat nutritious low fat foods such as lean meats, brown rice, fresh fruit, quinoa, legumes, and low-fat dairy products, but avoid low fat foods with made refined starches or sugars. After one year, both groups averaged significant weight loss, and saw improvement in various aspects of health such as lower blood pressure, reduced body fat, and reduced waist size. The low carb group averaged just over 13 pounds lost, while the low fat group averaged around 11.7 pounds lost. Some participants lost over 50 pounds.
Dr. Gardner emphasized that those who lost the most weight reported that the study had “changed their relationship with food,” cooking more at home and avoiding convenience eating. “We really stressed to both groups again and again that we wanted them to eat high-quality foods,” he said. “We told them all that we wanted them to minimize added sugar and refined grains and eat more vegetables and whole foods. We said, ‘Don’t go out and buy a low-fat brownie just because it says low fat. And those low-carb chips — don’t buy them, because they’re still chips and that’s gaming the system.’”
This study differs from many similar weight loss studies because it didn’t prescribe any specific limitations on the amount of food people ate. Participants weren’t given any calorie restrictions, and weren’t encouraged to consciously limit their food intake. Instead they were encouraged to satisfy their hunger by consuming high-quality whole foods and avoiding low-quality refined foods. Dr. Gardner noted that both groups did ultimately consume fewer calories by the end of the study, but emphasized that this was an effect of focusing on food quality, and participants weren’t conscious of it.
However, there are some limitations to the study. Both groups were asked to limit their fat or carbohydrate calories to 20 gm per day respectively. They were able to maintain these limits for the first two months of the study but found maintaining these ratios beyond that time challenging. In fact, by the third month of the study, the low carb group was consuming upwards of 100-gm of carbohydrates! Any ketogenic or fat adapted person would tell you that 100-gm of carbohydrates is by no means a low carb group!
If you are familiar with the nutritional approach to biohacking or ketogenic diets, this study may not come as a surprise. Biohackers and proponents of the keto method have long understood the relationship between high quality nutrition and optimal health. But it is encouraging to see such widely publicized study touting the importance of nutritious whole foods. Perhaps in the future there will be a comparison of an actual low-fat vs low-carb group which attempts to maintain the appropriate ratios for the entire study to put this question to rest once and for all.