Fat Guide
The hidden risks of very low-fat diets
Cutting fat too aggressively doesn't just make food taste worse — it can quietly undercut hormone production and vitamin absorption.
- Reduced hormone production — steroid hormones like testosterone and estrogen are synthesized from cholesterol, and a meta-analysis of intervention studies found men on low-fat diets (~20% of calories) had measurably lower testosterone than men on higher-fat diets (~40%).[1]
- Poor absorption of vitamins A, D, E, and K — these fat-soluble vitamins require dietary fat to be absorbed, regardless of how much you're eating in your food.[2]
- Essential fatty acid shortfalls — omega-3 and omega-6 fats can't be made by your body and must come from food[3]
- Menstrual irregularities — very low fat and low overall energy intake are linked with disrupted cycles
- Poor diet adherence — fat slows digestion and increases satiety; very low-fat diets are often harder to stick to long-term
The fix isn't complicated: stay within the recommended 20–35% of calories from fat rather than pushing dramatically lower.
Keep reading: What fat actually does · How much fat per day · Healthy high-fat foods