Diet composition matters a little for testosterone; body fat matters a lot. And the honest supplement bottom line is a good deal less exciting than the marketing — worth stating plainly before anyone spends money.
Very-low-fat diets may modestly lower testosterone (dietary fat and cholesterol are the raw material for making it), so there's no case for cutting fat to zero. Just as important: chronic under-eating lowers testosterone, especially in already-lean men — the axis reads a large energy deficit as a reason to down-regulate. Don't crash-diet for testosterone if you're not carrying excess fat. Overall, macronutrient effects are small next to body fat. Evidence ●●●○○
No supplement reliably raises testosterone in a healthy, lean, replete man. Supplements earn a place only by correcting a real deficiency (vitamin D, zinc) or by easing stress and sleep (ashwagandha) — modest effects at best. The levers that move testosterone meaningfully are losing excess fat, sleeping enough, and cutting heavy alcohol. Anything promising a big natural jump in an already-healthy man is overselling.
The honest hierarchy
Fat loss and sleep sit far above everything else, deficiency correction (D, zinc) is a distant second, and adaptogens are a minor third. The men who see real gains from any of this are the ones with the most to fix; if you're already lean, rested and sober, there's little left for a supplement to add.
The Testosterone Guide