Turning 40 does not require a new set of food rules. There is no universal metabolic cliff at this birthday, although your individual needs can change. 1

The useful focus is protecting strength, meeting nutrient needs and responding to symptoms, rather than assuming your previous diet has stopped working.

Age-related metabolic changes

A large study found that energy expenditure, adjusted for body composition, was broadly stable between ages 20 and 60. It does not support a sudden metabolic slowdown at 40. 1

This was a population study, not a prediction for each person. Changes in activity and body composition can still alter how much food you need. 1

Eating less is not automatically necessary. If your energy needs fall, preserve nutritious foods rather than simply shrinking every meal. NZ guidance emphasises both food quality and appropriate amounts. 3

Sarcopenia prevention

Sarcopenia involves loss of skeletal muscle and function. In older adults, anabolic resistance means a reduced muscle-building response to food and exercise, not an inability to improve. 2

It is not too late to start at 50. Combine adequate nutrition with progressive resistance training. NZ adult guidance recommends muscle-strengthening activity on at least two days each week. 2 3

For healthy adults strength training, around 1.6 g of protein per kilogram of bodyweight daily is a useful planning target. It is not a requirement that begins at 40. 4

For a 70 kg person, that is about 112 g daily. The research estimated a plateau in additional fat-free-mass gains, not a precise threshold for everyone. Fat-free mass is not synonymous with skeletal muscle. 4

Include protein across meals rather than leaving most for dinner. Dairy, eggs, fish and lean meat provide essential amino acids, including leucine; soy and legumes also contribute protein. 2 3

Treat meal distribution as a practical habit, not a proven anti-ageing formula. Illness and kidney disease can change suitable protein advice. 2

See our guide to protein targets, timing and food sources.

Bone density and nutrition

Bone health deserves attention before a fracture occurs. Menopause can bring loss of bone density, making nutrition and appropriate activity important parts of midlife care. 3 8

Australia and NZ calcium reference intakes are 1,000 mg daily for adults aged 19 to 50 and men aged 51 to 70. Women aged 51 and older, and men aged 71 and older, need 1,300 mg. 5

These are total intakes, not supplement doses. Useful foods include milk, yoghurt, calcium-fortified alternatives and canned fish with edible bones. Check labels when choosing alternatives. 3 5

Vitamin D supports calcium regulation and bone health. Discuss supplementation if you have limited sun exposure or other deficiency risks, rather than automatically taking 1,000 to 2,000 IU daily. 6

Vitamin K helps bone-related proteins function, but K2 supplements are not established as a way to prevent osteoporosis or direct calcium away from arteries. Mechanisms are not guaranteed clinical benefits. 7

For local context, read vitamin D in New Zealand.

Hormonal shifts

Perimenopause can affect sleep, mood and body shape, with weight gain often occurring around the abdomen. Experiences vary, and these changes do not mean food choices have suddenly become ineffective. 8

Keep the same foundations: adequate protein, calcium-rich foods and regular activity. Nutrition supports health, but disruptive symptoms deserve a conversation with your GP, not simply a stricter diet. 3 8

Seek advice for heavier or changed bleeding, or any vaginal bleeding after 12 months without a period. These should not be managed through nutrition alone. 8

For men, fatigue or body-composition changes do not diagnose low testosterone. Assessment requires compatible symptoms and consistently low levels, confirmed with repeat morning testing. 9

Explore perimenopause and body composition for more detail.

Put it into practice

Start with a few repeatable actions:

  • Include a protein food at each main meal. 2
  • Eat vegetables, fruit, wholegrains and calcium-rich foods regularly. 3
  • Schedule at least two strength-training days and build up gradually. 3
  • Adjust portions to your needs rather than cutting food because of your age. 1 3

For support turning these priorities into a routine, explore our Longevity Programme.