Bone is built and held by mechanical load and adequate amino acids. After fifty, both tend to fall. Most women are below the threshold for either. Here is what the threshold actually is.

The drop nobody warns you about

Bone is living tissue. Osteoblasts build it, osteoclasts break it down, and the balance shifts with hormones, load, and protein supply. Through the late forties and into menopause, oestrogen falls, and with it the brake on bone resorption. The first five to seven years post-menopause are the steepest period of loss for most NZ women.

The standard advice arrives late and lands light: take calcium, do some walking, get a DEXA at sixty-five. By then, a decade of preventable loss has already happened.

Across the women we coach, those who hold bone density into their sixties and seventies share two habits the average woman does not: they eat enough protein, and they load their skeleton hard enough to matter.

The protein threshold

The Ministry of Health RDI for protein sits around 0.8 g per kg of body weight. That number was set to prevent deficiency in healthy young adults. It was never the threshold for preserving bone and muscle in a sixty-year-old.

The research on protein and bone in post-menopausal women points to a different floor. For maintenance of lean mass and bone matrix, intakes of 1.6 to 2.2 g per kg of body weight per day track with better outcomes. For a 65 kg woman, that is roughly 100 to 145 g of protein per day.

In our intake reviews with women over fifty, the typical starting point is 50 to 70 g per day. That is not a small gap. That is half of what the body needs to maintain the collagen scaffold bone is built on.

Bone is not just calcium. The matrix is roughly 50% protein by volume, predominantly type I collagen. Without the amino acid supply, the mineral has nothing to bind to.

Load is the other half

Protein gives the raw material. Load gives the signal to use it. Without mechanical stress, osteoblasts have no reason to lay down new tissue, regardless of how much protein is on the plate.

Walking is not load. It maintains cardiovascular function and is worth doing, but the strain it places on the femur and spine is below the threshold that triggers bone formation in a post-menopausal skeleton.

What works:

  • Resistance training with progressive load: squats, deadlifts, presses, rows, performed at intensities that genuinely challenge the working muscles.
  • Impact work where joints allow: jumps, hops, skipping, two to three sessions per week.
  • Compound movements over machines, because axial loading of the spine and hip is where the gain shows up on DEXA.

Two sessions per week is a floor. Three is better. The women in our coaching cohort who reverse early osteopenia are training heavy, not light.

Bone responds to two inputs: amino acids on the plate and force through the skeleton. Reduce either below threshold and the scan will show it within eighteen months.

The labs and scans we track

DEXA is the gold standard for bone density. For women in the perimenopausal and early post-menopausal window, a baseline scan in the late forties or early fifties is far more useful than waiting until sixty-five. You cannot manage what you have not measured.

Cadence we work with, alongside your GP:

  • DEXA every 18 to 24 months through the menopause transition, then every 2 to 3 years once stable.
  • Bloods including 25-OH vitamin D, calcium, magnesium, PTH, and thyroid markers.
  • CTX or P1NP where bone turnover is in question, ordered through your GP.

BIA scans in our Christchurch rooms track lean mass alongside fat mass. Lean mass is the closest proxy we have between DEXA appointments for whether the protein and training are doing their job. Losing lean mass in your fifties almost always means losing bone with it.

Where NZ women get stuck

Three patterns show up repeatedly in the 1,300+ clients we have worked with:

The breakfast gap. Toast, fruit, a flat white. Maybe 8 g of protein before noon. The body has been fasting for twelve hours and the first meal does not trigger meaningful muscle protein synthesis.

The training mismatch. Pilates, yoga, walking, a gym class once a week. Excellent for mobility and aerobic base. Insufficient as a bone-loading stimulus on their own.

The HRT question. For some women, hormone therapy is part of the picture, and that is a conversation with your GP. Nutrition and training do not replace HRT where it is indicated, and HRT does not replace nutrition and training. They compound.

What to do this week

  • Weigh your protein at one meal for three days. Most women find they are eating half of what they assumed.
  • Set a floor of 30 g of protein at breakfast. Eggs, Greek yoghurt, cottage cheese, or a whey shake clear it without effort.
  • Book or schedule two resistance sessions this week with compound lifts: squat, hinge, press, pull. Heavy enough that the last two reps are hard.
  • If you are over fifty and have never had a DEXA, ask your GP for a referral or arrange one privately. Get the baseline.
  • Track lean mass alongside weight. The scale alone will mislead you through this decade.