Discussions of dietary fat on steroids often focus on protein and carbohydrates, leaving fat as an afterthought. That is a mistake for two concrete reasons: cutting fat too low is associated with lower testosterone, and the type of fat eaten affects blood cholesterol, which anabolic-androgenic steroids (AAS) already push in an unfavorable direction.
This article explains what dietary fat does in the body, what research shows about very low fat intakes, why fat quality matters particularly for people using AAS, and what reasonable intake looks like.
What does dietary fat actually do?
Fat has several roles that carbohydrates and protein cannot fill.
Essential fatty acids. The body cannot make linoleic acid (an omega-6 fat) or alpha-linolenic acid (an omega-3 fat), so they have to come from food. They are used to build cell membranes and to produce signaling molecules involved in inflammation and immune function.
Fat-soluble vitamin absorption. Vitamins A, D, E, and K need dietary fat to be absorbed properly. A very low fat intake can therefore affect vitamin status even when the diet contains those vitamins.
Cell membranes. Every cell membrane is built largely from fats, and membrane composition affects how cells respond to signals, including hormonal ones.
Energy density. Fat provides about 9 calories per gram, compared with 4 for protein and carbohydrate, which matters when energy needs are high.
Does low fat intake lower testosterone?
Evidence suggests it can. A systematic review and meta-analysis of six controlled crossover studies, involving 206 men, found that total and free testosterone were roughly 10% to 15% lower on low-fat diets (around 20% of calories from fat) than on higher-fat diets (around 40%). Dihydrotestosterone also decreased, which points to reduced production rather than a change in how testosterone is carried in the blood (Whittaker & Wu, 2021).
The studies were small, the men’s testosterone remained within the normal range, and the authors called for further randomized trials, so this should not be overstated. It is reasonable evidence that very low fat intakes are unhelpful, not evidence that eating more fat raises testosterone beyond normal.
The caveat for AAS users
This finding is often repeated in bodybuilding contexts as a reason to eat more fat “on cycle.” That reasoning does not hold. AAS suppress the body’s own testosterone production regardless of diet, so dietary fat cannot protect natural production during use. Our article on testosterone recovery after steroids explains how that suppression works.
Where fat intake does matter is afterwards, when natural production is recovering, and for general health throughout.
Why fat quality matters more, not less
This is the most practical point for anyone using AAS. Steroid use is strongly associated with reduced HDL cholesterol and often increased LDL cholesterol, as covered in our article on how steroids affect cholesterol levels.
Because that shift is already unfavorable, the type of fat in the diet carries more weight than it would otherwise:
Unsaturated fats, from olive oil, nuts, seeds, avocados, and oily fish, are associated with a more favorable lipid profile when they replace saturated fat.
Saturated fat, from fatty meat, butter, and full-fat dairy, raises LDL cholesterol when it makes up a large share of intake.
Trans fats, found in some processed foods, raise LDL and lower HDL, and are best avoided.
Diet will not offset the lipid effects of AAS, and no fat source protects against them. But adding a diet that also pushes LDL upward compounds a risk that is already raised.
What about omega-3 fats?
Omega-3 fats from oily fish are associated with lower triglycerides and are part of general heart-health advice. They are a sensible inclusion, particularly given AAS-related cardiovascular risks discussed in our article on steroids and heart health.
Claims that omega-3 supplements meaningfully improve muscle growth or recovery are not well supported. Treat them as general nutrition rather than a performance supplement.
How much fat is reasonable?
General dietary guidance for adults puts fat at roughly 20% to 35% of total calories, with saturated fat kept below about 10%. For most people who train, staying within that range while meeting protein needs is enough.
The main practical point is to avoid pushing fat very low in an attempt to fit more carbohydrate or protein into a calorie target. Below roughly 20% of calories, essential fatty acid intake, fat-soluble vitamin absorption, and hormone production all become harder to support.
Individual needs vary with total energy intake, body size, and health conditions. Anyone with raised cholesterol, cardiovascular risk factors, or specific medical advice about fat intake should follow their doctor or dietitian rather than general guidance.
What fat intake cannot do
Dietary fat does not increase muscle growth directly, does not counteract the hormonal suppression caused by AAS, and does not protect the liver, heart, or cholesterol profile from the effects of steroid use. Supplements marketed for these purposes are discussed in our article on vitamins and minerals for steroid users.
Fat is a requirement to meet, not a lever to pull.
The bottom line
Dietary fat on steroids matters for reasons that have nothing to do with performance claims. Fat supplies essential fatty acids, enables absorption of vitamins A, D, E, and K, and supports the body’s own hormone production, which research suggests is reduced by roughly 10% to 15% on very low fat diets.
For people using AAS, the more immediate issue is fat quality. Steroid use already lowers HDL cholesterol and often raises LDL, so a diet high in saturated and trans fats adds to a risk that is already elevated. Keeping fat within normal dietary ranges, favoring unsaturated sources, is sensible nutrition rather than a cycle strategy.
References
Whittaker J, Wu K. Low-fat diets and testosterone in men: systematic review and meta-analysis of intervention studies. The Journal of Steroid Biochemistry and Molecular Biology. 2021;210:105878.
