Exercise and nutrition after 40: what the research actually shows.

The macro calculator on this site gives you a calorie and protein target. Those numbers are grounded in current research, but the research also makes something else very clear: nutrition targets work significantly better when paired with regular physical activity, particularly resistance training.

This article summarises what the peer-reviewed literature shows about how exercise and nutrition interact after 40, and what the Australian Government's physical activity guidelines recommend for adults in this age group.

Why exercise and nutrition cannot be considered separately after 40

Age-related muscle loss, known as sarcopenia, begins from around age 40 and accelerates after 60. Research consistently shows that adults lose approximately 3 to 8% of muscle mass per decade after 40.[2] Both higher protein intake and regular resistance exercise independently help slow this process. The evidence is clear, however, that the combination of the two produces outcomes that neither achieves alone.

A 2022 analysis published in the Journal of Cachexia, Sarcopenia and Muscle found that only a protein intake above 1.6g per kg of body weight per day, combined with resistance training, was consistently associated with improvements in muscle strength in older adults.[3] Protein without exercise, or exercise without adequate protein, produces a measurably smaller response.

The underlying mechanism is well established. Resistance exercise creates a stimulus for the muscle to rebuild and adapt. Dietary protein provides the amino acid building blocks the body uses to complete that process. When the stimulus is present but the building materials are insufficient, or vice versa, the full adaptation does not occur.[4]

What the Australian physical activity guidelines say

The Australian Government Department of Health's physical activity guidelines for adults aged 18 to 64 recommend accumulating between 2.5 and 5 hours of moderate-intensity physical activity per week, or between 1.25 and 2.5 hours of vigorous-intensity physical activity per week, or an equivalent combination of both. The guidelines also specifically recommend muscle-strengthening activities on at least two days per week.[5]

For adults aged 65 and over, the guidelines recommend being active every day in as many ways as possible, incorporating fitness, strength, balance and flexibility, with at minimum 30 minutes of moderate-intensity physical activity on most, preferably all, days.[5]

Despite these recommendations, ABS National Health Survey data from 2022 found that only 22.4% of Australian adults aged 18 to 64 met both the aerobic and muscle-strengthening components of the physical activity guidelines. Only 26.6% of adults reported undertaking strength or toning exercises on two or more days in the previous week.[6]

What "resistance training" means in this context

The research on muscle preservation in older adults uses the term resistance training to describe activities that place a load on the muscles, causing them to work against resistance. This includes lifting free weights, using weight machines, performing bodyweight exercises such as squats and push-ups, and using resistance bands.[7]

The research does not prescribe specific programs. What it consistently shows is that some form of regular resistance-based activity, combined with adequate dietary protein, is associated with better muscle mass outcomes in adults over 40 than aerobic exercise alone or a sedentary lifestyle.[7]

Aerobic exercise and its distinct role

While resistance training is the primary stimulus for muscle preservation, aerobic exercise plays a distinct and important role in cardiovascular health, metabolic function and overall energy expenditure. The Australian guidelines do not recommend one at the expense of the other. Adults over 40 are recommended to include both.[5]

Research published in Frontiers in Physiology notes that combined aerobic and resistance training produces broader health benefits across cardiometabolic, musculoskeletal and functional outcomes than either type alone, particularly in middle-aged and older adults.[8]

How exercise affects calorie and macro targets

Activity level is one of the primary inputs in the macro calculator on this site. The more physically active a person is, the higher their total daily energy expenditure, which adjusts their calorie and macro targets accordingly.

From a protein perspective, the current body of research suggests that adults who engage in regular resistance training may need protein at the higher end of the recommended range, closer to 1.6g per kg of body weight per day, to support both muscle repair after training and ongoing muscle preservation.[3] This is the figure the calculator uses by default for fat loss and muscle building goals.

Physical activity and the Australian over-40 population

The same population-level data showing widespread dietary inadequacy in Australian adults over 40 also reveals a gap in physical activity. The Australian Institute of Health and Welfare reports that over half of all Australian adults lead a sedentary lifestyle, with physical inactivity increasing with age.[9]

The combination of declining physical activity and falling short of protein targets, both common in this age group, creates the conditions in which sarcopenia accelerates most rapidly.[2]

What the research does not show

It is worth being clear about what the evidence does not establish. The research on exercise and nutrition in older adults demonstrates associations and average effects across study populations. It does not prescribe specific exercise programs, specific meal structures, or specific timelines for individuals. Individual responses to exercise vary depending on genetics, health status, baseline fitness and many other factors.[4]

The research also does not suggest that exercise alone is sufficient to offset a significant protein deficit, or that high protein intake alone compensates for a sedentary lifestyle. The two work together, and the evidence consistently favours addressing both.[1]