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Low-fat diet Redux at WHO.
David S Ludwig1, Frank B Hu2, Alice H Lichtenstein3
1New Balance Foundation Obesity Prevention Center, Boston Children's Hospital, Boston, MA, United States; Harvard Medical School, Boston, MA, United States; Department of Nutrition, Harvard T.H. Chan School of Public Health, MA, United States; Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
The American Journal of Clinical Nutrition
|September 24, 2023
Summary
Dietary fat does not directly cause weight gain, contrary to past low-fat diet guidelines. Replacing fats with carbohydrates may worsen insulin resistance and heart health, warranting a review of fat intake recommendations.
Area of Science:
- Nutrition Science
- Metabolic Health
- Public Health Guidelines
Background:
- Late 20th-century dietary guidelines recommended low-fat diets, assuming fat intake causes obesity.
- This notion was partly based on fat being the most energy-dense macronutrient.
- Recent evidence challenges the direct link between dietary fat and adiposity.
Purpose of the Study:
- To evaluate the association between dietary fat intake and body weight.
- To examine the metabolic consequences of substituting carbohydrates for unsaturated fats.
- To reassess current recommendations on dietary fat limits.
Main Methods:
- Review of high-quality evidence on dietary fat and adiposity.
- Analysis of studies investigating carbohydrate-fat substitution effects on metabolic health.
- Critical evaluation of existing public health dietary guidelines.
Main Results:
- High-quality evidence refutes a direct association between dietary fat and adiposity.
- Substitution of unsaturated fats with carbohydrates can increase insulin resistance.
- These effects are particularly pronounced in populations with high insulin resistance.
Conclusions:
- The prevailing low-fat dietary recommendations are not supported by current evidence.
- Limiting dietary fat may have adverse metabolic consequences, including increased insulin resistance.
- The World Health Organization's recommendation to limit dietary fat to 30% warrants reconsideration.