It Is Not Just About Your Blood Testosterone Level
What does “optimising” your testosterone actually mean? Most people assume this means having a high “total testosterone” reading on a blood test. But your total testosterone is only part of the picture.
A significant portion of testosterone in your blood is bound to a protein called “sex hormone-binding globulin” (SHBG), which makes it “biologically inactive” (meaning it doesn’t interact with your body).
Only "free" testosterone (not bound to anything) is actually available for your body to use.
You can have a normal total testosterone reading while still experiencing the effects of low testosterone if your SHBG is too high or if your body's hormonal signalling is disrupted in some way.
Testosterone is produced in your testes, but the amount you produce is controlled by your brain, which is sensitive to your nutritional state, stress levels, sleep and body composition.
So if you want to optimise your testosterone, it is really a “whole systems” approach — not just manipulating a single marker on a lab report.
Signs Your Testosterone May Be Low
Low testosterone is not also clear or easy to diagnose from its symptoms, but some of the most common signs include [1]:
- Persistent low energy or fatigue, even with adequate sleep
- Reduced sex drive or difficulty with erections
- Poor sports performance, muscle loss or difficulty building muscle.
- Increased body fat, particularly around the abdomen
- Low mood, irritability, or difficulty concentrating
If several of these sound familiar, your diet could be a contributing factor. However, the good news is that nutritional changes can improve your testosterone, often within weeks.
How Diet Affects Testosterone
Testosterone is made from cholesterol. This means your body cannot produce testosterone without adequate amounts of dietary fat. Eating too little fat reduces the availability of this building block and will blunt the production of testosterone.
Beyond fat, your overall calorie intake acts as a signal to your testosterone production system. When calories drop too low, your body interprets this as a famine-like state and goes into "survival mode".
Your body will dial down your testosterone production; this can happen in just a few days of aggressive energy deficit [2].
Several micronutrients (like zinc, magnesium and vitamin D) are required in certain amounts to produce testosterone. If you are deficient in any of these micros, your production of testosterone will slow or stop.
Correcting these deficiencies can restore normal testosterone levels, but mega-dosing beyond adequate amounts doesn’t seem to speed up or increase testosterone production.
What to Eat to Support Testosterone
Prioritise Dietary Fat
Aim for 25–35% of your total daily calories from fat. Evidence shows that very low-fat diets (below 20% of calories from fat) can reduce testosterone levels [3]. Like the micronutrients, eating a high-fat diet (say, beyond 35%) does not further increase your testosterone levels.
The type of fat also matters, so you want to ensure you are eating enough saturated fats (e.g., eggs, red meat, full-fat dairy, and coconut oil), monounsaturated fats (e.g., olive oil, avocado, and nuts) and omega-3 fatty acids from oily fish.
Eat Enough Calories
If your goal is to optimise testosterone while maintaining a healthy bodyweight, keep any calorie deficit less than 20% below maintenance, and avoid sustained dieting for more than a few months at a time.
Strategic "re-feed" periods every two to four weeks can help restore hormonal function [2].
Eat Enough Zinc, Magnesium & Vitamin D
Good dietary sources of zinc include oysters (the richest source by far), red meat, poultry, pumpkin seeds, beans, and whole grains. Vegetarians and men who train heavily, pay attention, because they are at higher risk of zinc deficiency, as zinc is lost through sweat [4].
For magnesium, which is required for loads of bodily functions (including testosterone production), eat leafy greens, nuts and seeds, whole grains, legumes, and dark chocolate. Magnesium may also improve your sleep quality, which is important for testosterone production as well.
Vitamin D acts as a hormone, stimulating testosterone production in itself (up to a point). Eat fatty fish and eggs, but sunlight exposure is the most potent source of vitamin D.
If you live in northern latitudes and spend limited time outdoors, you may have to look at vitamin D supplementation [5].
High Quality Protein, Not Too Much or Too Little
Protein doesn’t directly drive testosterone production, but it is required to support and build muscle, recovery and a healthy body composition.
Aim for 1.6–2.2 g per kilogram of bodyweight per day from whole food sources like meat, fish, eggs, and legumes. Note that very high protein intakes (above 3.4 g/kg/day) may actually reduce testosterone levels; so again, more isn’t always better [6].
What to Avoid
Aggressive Calorie Restriction
An ultra-low-calorie diet, particularly one combined with heavy training, is one of the fastest ways to suppress testosterone [2]. Your endocrine system cannot distinguish between intentional dieting and genuine food scarcity. If you need to lose fat, do it slowly.
Very Low-Fat Diets
Diets providing less than 20% of calories from fat have been shown to reduce testosterone levels [3]. Fat-phobic eating patterns (that are common in some physique sports and fitness communities) can quietly undermine your testosterone levels.
Excess Alcohol
Regular heavy alcohol consumption suppresses testosterone production and disrupts your sleep, further compounding its disruptive effect. Occasional moderate drinking is unlikely to cause significant issues, but regular heavy use can [7].
Too Much Body Fat
Fat tissue, particularly visceral (abdominal) fat, converts testosterone to oestrogen via an enzyme called aromatase. Carrying too much body fat suppresses testosterone. So if you’re overweight, losing fat is one of the most effective things you can do for your testosterone levels.
Supplements That Work (and Ones That Don't)
Ashwagandha supplementation increases total and free testosterone, particularly for older men, stressed men, or men with low-testosterone symptoms [8]. Its effects are modest as it works (indirectly) by reducing cortisol (which suppresses testosterone) rather than directly stimulating testosterone production.
Fenugreek extract has been shown to increase testosterone by reducing the amount on a enzyme in the body that converts testosterone into estrogen [9]. Results for zinc, magnesium, vitamin D, and omega-3 supplements are mixed, and only likely to raise your testosterone levels if you’re deficient in them to start with.
Despite the aggressive marketing, there is little evidence that most (so-called) testosterone boosters actually boost your testosterone, or even contain testosterone-boosting ingredients. In fact, some of these products contain things that may disrupt testosterone production [10].