The idea that metabolism falls off a cliff at 40 is not supported by the data, total energy expenditure is remarkably stable from about 20 to 60 once body composition is accounted for. What does change is muscle mass, activity, recovery and alcohol tolerance, and those change what a sensible diet looks like.
Protein: more important, more often
Ageing muscle responds less strongly to a given dose of protein. Meeting roughly 1.2 to 1.6 g per kg of body weight per day, distributed across meals rather than concentrated at dinner, supports muscle maintenance alongside resistance training.
In practice this usually means adding protein to breakfast, which is where most men's intake is lowest.
Fibre: the most underrated number
Most men consume roughly half the recommended 30 g or more of fibre per day. Higher intake is consistently associated with lower cardiovascular risk, better glycaemic control, improved satiety and lower colorectal cancer risk.
Legumes, whole grains, vegetables, fruit, nuts and seeds do this without any need for a supplement.
The patterns with the strongest evidence
Nutrition science supports patterns more strongly than individual foods. Mediterranean-style and DASH-style eating both have substantial trial and cohort support for cardiovascular and metabolic outcomes.
- Mostly minimally processed foods, with plants forming the bulk of volume.
- Unsaturated fats (olive oil, nuts, fatty fish) in place of most saturated fat.
- Limited added sugar, refined grains and processed meat.
- Sodium moderation, which matters more once blood pressure is drifting up.
Alcohol after 40
Alcohol contributes calories, raises triglycerides and blood pressure, disrupts the second half of the night's sleep and adds liver fat. Recent evidence has steadily weakened the claim that moderate drinking is protective.
For many men over 40, reducing alcohol produces visible movement in weight, blood pressure, sleep quality and liver enzymes within weeks, often more than any supplement they were considering.
Supplements: a short honest list
Supplements are worth taking when they correct a measured deficiency or a documented gap, not as a hedge. Vitamin D when deficient, vitamin B12 for those on plant-based diets or certain medications, and omega-3 for men who eat no fish are the usual candidates.
Products marketed for testosterone or 'male performance' are the highest-risk category, as several have been found to contain undeclared prescription ingredients.
Key takeaways
- Total metabolism is stable through midlife; body composition and activity are what change.
- Aim for 1.2 to 1.6 g/kg protein per day, spread across meals.
- Most men fall far short on fibre: 30 g or more per day is the target.
- Mediterranean and DASH-style patterns have the strongest outcome evidence.
- Cutting alcohol often improves weight, blood pressure, sleep and liver markers quickly.
References
- Dietary Guidelines for Americans. Dietary Guidelines for Americans, 2020–2025
- American Heart Association. Dietary Guidance to Improve Cardiovascular Health
- World Health Organization. No level of alcohol consumption is safe for our health
How this article is reviewed
Aldrick articles are written from published guidance and peer-reviewed research, checked against our evidence standards and re-reviewed when guidance changes. Spotted something inaccurate or out of date? Tell us and we will correct it and update the review date.
This article is educational. It does not diagnose conditions or replace evaluation by a qualified clinician.