The threshold most coaching guides quote is below what the research now supports. Lean mass holds the decade. Protein is what holds the lean mass. For most women over 40, the working number is 1.6 to 2.2 grams per kilogram of body weight per day, distributed across three or four meals that each clear a leucine threshold.

The short answer

A 70 kg woman over 40 needs roughly 110 to 150 grams of protein per day to defend lean mass and support training. That sits well above the RDA of 0.8 g/kg, which was set to prevent deficiency, not to preserve muscle through perimenopause and beyond.

The reason the number climbs with age is anabolic resistance. Older muscle responds less efficiently to a given dose of protein. You need more leucine per meal to trigger the same muscle protein synthesis response a 25-year-old gets from less. The fix is dose and frequency, not heroic single meals.

Why 40 is the inflection point

Women begin losing lean mass slowly from the mid-30s. The drop accelerates through perimenopause as oestrogen falls and recovery from training lengthens. Bone density tracks the same curve. Across our BIA scans at Inception, the women who hold lean mass into their 50s and 60s share two habits: they lift, and they eat protein at every meal.

Sarcopenia is not a disease that begins at 70. It begins in your 40s as a quiet trend on a scan. By the time it shows up in how you carry shopping or get off the floor, a decade of loss has already happened.

The meal-by-meal threshold

Total daily protein matters. Distribution matters almost as much. Each meal needs roughly 0.4 g/kg of protein to maximally stimulate muscle protein synthesis in women over 40. For a 70 kg woman, that is around 30 grams of protein per meal, three to four times a day.

Practical anchors:

  • Breakfast: 30 g (two eggs plus 150 g Greek yoghurt, or 150 g cottage cheese on toast)
  • Lunch: 35 g (120 g chicken breast or tinned salmon with salad)
  • Dinner: 40 g (150 g beef, lamb, or firm white fish)
  • Optional snack: 20 to 25 g (whey shake, edamame, or biltong)

Skipping breakfast protein and loading dinner is the most common pattern we see in intake reviews. It hits the daily total but misses two of the three anabolic windows.

Total protein wins the week. Protein per meal wins the decade.

What this looks like on an NZ pantry

The 2,846-food dataset we use for client planning makes this concrete. You do not need imported powders or specialty products to hit the number. You need to know what each staple actually delivers.

High-yield NZ options per 100 g cooked:

  • Chicken breast: 31 g
  • Beef mince (lean): 26 g
  • Hoki, tarakihi, or snapper: 22 to 24 g
  • Tinned tuna or salmon: 25 to 28 g
  • Eggs: 13 g (two large eggs, around 12 g)
  • Greek yoghurt (unsweetened): 9 to 10 g
  • Cottage cheese: 11 g
  • Edamame: 11 g
  • Tofu (firm): 12 to 15 g

Kūmara, rice, and oats are useful carbs but contribute little protein. Treat them as fuel, not as part of the protein count.

Plant-only eaters need to push the upper end of the range, around 2.0 to 2.2 g/kg, because plant proteins are lower in leucine and less digestible. Combining legumes with tofu, tempeh, and a quality protein powder closes the gap.

Common objections, answered

"Won't that much protein damage my kidneys?" In healthy women without pre-existing kidney disease, intakes up to 2.2 g/kg show no adverse effect on renal function in the literature. If you have known kidney issues, we work alongside your GP and adjust accordingly.

"I'm not trying to build muscle, just stay lean." Holding lean mass is the goal for most women over 40. You are not building, you are defending. The protein requirement to defend tissue under the hormonal shifts of perimenopause is higher than the requirement to maintain it at 25.

"I get full quickly." That is a real constraint, not an excuse. Protein is the most satiating macronutrient, which is useful for fat loss and inconvenient for hitting a target. The fix is front-loading. Start the day with 30 to 40 g before appetite-suppressing coffee and a busy morning push lunch into mid-afternoon.

Training changes the equation

Protein without resistance training preserves less than protein with it. The signal to keep muscle is mechanical load. Two to four sessions per week of progressive lifting, focused on compound movements, multiplies the return on every gram of protein you eat.

Cardio alone, including walking, running, and cycling, does not provide that signal. It is good for cardiovascular health and energy expenditure. It is not a substitute for lifting when the goal is lean mass through your 40s, 50s, and 60s.

What to do this week

  • Weigh yourself once, multiply by 1.6, and use that number as your daily protein floor in grams.
  • Track three days of intake honestly. Most women find they are 30 to 50 g short of the floor.
  • Add a 30 g protein anchor to breakfast before adjusting anything else.
  • Book or repeat a BIA scan to establish your current lean mass baseline. You cannot defend a number you have not measured.
  • If you are not lifting twice a week, start. The protein only works if the signal is there.