Brigham and Women's Hospital
Researchers conducted a systematic review of randomized clinical trials comparing the long-term effectiveness of low-fat and higher-fat dietary interventions on weight loss.
The effectiveness of low-fat diet on weight-loss has been
debated for decades, and hundreds of randomized clinical trials aimed at
evaluating this issue have been conducted with mixed results.
Researchers from
Brigham and Women's Hospital (BWH) and the Harvard T.H. Chan School of Public
Health (HSPH) conducted a comprehensive review of the data generated from
randomized clinical trials that explored the efficacy of a low-fat diet and
found that low-fat interventions were no more successful than higher-fat
interventions in achieving and maintaining weight loss for periods longer than
one year.
"Despite the pervasive dogma that one needs to cut fat from
their diet in order to lose weight, the existing scientific evidence does not
support low-fat diets over other dietary interventions for long-term weight
loss," said Deirdre Tobias, ScD, a researcher in the Division of
Preventive Medicine at BWH.
"In fact, we did not find evidence that is
particularly supportive of any specific proportion of calories from fat for
meaningful long-term weight loss. We need to look beyond the ratios of calories
from fat, carbs, and protein to a discussion of healthy eating patterns, whole
foods, and portion sizes. Finding new ways to improve diet adherence for the
long-term and preventing weight gain in the first place are important strategies
for maintaining a healthy weight."
In this meta analysis of randomized clinical trials comparing
the long term effect (longer than one year) of low-fat and higher-fat dietary
interventions, researchers analyzed data from 53 studies with a total of 68,128
participants that were designed to measure the difference in weight change
between two groups that had a dietary intervention (low-fat or other diet).
Trials that included dietary supplements or meal replacement drinks were
excluded from the analysis. On average, trial participants across all
intervention groups only managed to lose and keep off six pounds at one year or
longer.
Compared with low-fat diets, participants in low-carbohydrate weight
loss interventions were about two and a half pounds lighter after follow-up of
at least one year.
Researchers also report that low-fat diets led to a greater
weight loss only when compared to 'usual diet' in which participants did not
change their eating habits.
"Current evidence indicates that clinically meaningful
weight loss can be achieved with a variety of dietary approaches," said
Frank Hu, senior author of the paper and Professor of Nutrition and
Epidemiology at Harvard T.H. Chan School of Public Health.
"The key is to
improve long-term compliance and cardiometabolic health. Therefore, weight loss
diets should be tailored to cultural and food preferences and health conditions
of the individual and should also consider long-term health consequences of the
diets."
This research was funded by the National Institutes of Health
(DK082730, HL34594, HL60712, CA176726, DK58845, DK46200, DK103720, and
CA155626) and the American Diabetes Association.
