Updated: Mar 10, 2019
Recently there was a study organized by David Ludwig of Boston Children's Hospital. They were looking to see if changing the carbohydrate to fat ratio in the diet would change metabolic rate after weight loss. They studied more than 160 participants for 20 weeks after a weight loss diet. The results of this are important because people often slow down their metabolic rate when dieting the old-fashioned way by simply reducing calories. This leads many to re-gain the weight due to lower energy needs.
Following the weight loss, in the second phase of the study the subjects were assigned a diet of either a 20, 40 or 60 percent of calories from carbohydrates with protein remaining stable at 20 percent.
What the study shows is that for every 10 percent increase in fat, and a corresponding decrease in carbohydrates in the diet, the study participants increased their metabolic rate by about 50 calories per day compared to people who were dieting and not reducing carbohydrates. Over time this was roughly a 200 calorie per day difference between the high carb and low carb groups.
Check out the study here.
It's important to note the study did not say people lost more weight on a low-carb diet — and didn't try to measure that. Meals and snacks were tightly controlled and continually adjusted so everyone's weight stayed stable. Ludwig said it suggests limiting carbs could make it easier for people to keep weight off once they've lost it.
He said the approach might work best for those with diabetes or pre-diabetes.
In this study, participants who were pre-diabetic responded more favorably to the reduction of carbohydrates. For some in the study, there was a 400 calorie per day increase in metabolism by eating high fat, low carb .
The take home message according to this study, is that if you are trying to keep weight off, simply keeping track of calories is probably not a great idea. All this suggests that the body adapts to a high fat, low carb diet by burning more fat and keeping the metabolism up.
So if you keep regaining weight, try a high fat low carb diet.