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
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
These results are published in The Lancet Diabetes &
Endocrinology on October 30, 2015.
"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
"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."
For more information
The Lancet Diabetes & Endocrinology
Brigham and Women's Hospital
Harvard T.H. Chan School of Public Health