, Writer and editor, MyGLP. Sources checked .

What happens to weight after 40

Oestrogen falls through the perimenopause, the years before periods stop. As it falls, fat is more likely to settle around the middle rather than the hips, and muscle is lost a little faster each year. Sleep often breaks up, and poor sleep pushes appetite up. None of that is a failure of willpower. The NHS menopause page lists weight gain among the common symptoms.

A weight loss medicine takes the appetite part out of the equation. In the big trials the average loss was similar for women across the age range. What the trials also showed is that a share of the weight lost is muscle, and after 40 you have less to spare.

HRT and the medicines

You can take HRT and a weight loss medicine together. Neither the NHS nor the medicine leaflets list HRT as a reason to avoid them. There is one practical point. Mounjaro slows the stomach, and the contraception rule is there because tablets may absorb less for a few weeks after a dose rise. HRT is not contraception, and oestrogen tablets are not covered by that rule, but if you take HRT by mouth and notice symptoms creeping back after a dose increase, say so. Patches, gels and sprays are absorbed through the skin and the slow stomach makes no difference to them.

NICE guideline NG23 on the menopause is the standard GPs work to. It says HRT is the first choice for hot flushes and night sweats, and it does not treat body weight as a reason to refuse it.

Muscle: the thing to keep

In the semaglutide trial that measured body composition, roughly two fifths of the weight lost was lean tissue rather than fat. For tirzepatide the figure was about a quarter. Lean tissue includes water and organ weight as well as muscle, but muscle is in there. After 40, lost muscle is harder to win back.

Two things slow the loss. Protein at every meal, which our protein guide sets out, and resistance exercise twice a week, which the UK Chief Medical Officers recommend for every adult. The strength guide shows how to do it at home with no kit.

Bone: the other thing to keep

Bone density drops fastest in the first years after periods stop, and fast weight loss adds to the drop. The Royal Osteoporosis Society puts the numbers plainly: women lose up to 10% of bone density in the five years after the menopause. Calcium of 700mg a day from food, vitamin D of 10 micrograms a day through autumn and winter, and weight-bearing exercise are the three levers. Our bone health guide goes through each.

Sleep, flushes and the medicines

Nausea and reflux from the medicine can be worse lying down, and night sweats already break sleep. Taking the weekly injection in the morning rather than at night, eating the evening meal early and keeping it small, and raising the head of the bed all help. Weight loss itself improves sleep apnoea, which is under-diagnosed in women at this age. Our sleep guide covers the detail.

Periods in the perimenopause on a jab

Cycles are already irregular at this stage, and weight loss can make them more so for a few months. Bleeding after 12 months without a period, or bleeding between periods, needs a GP appointment whatever medicine you take. The NHS treats bleeding after the menopause as a reason to be seen within two weeks.

A checklist for your 40s and 50s

  • Protein at every meal, around 1.2 to 1.6g per kg of body weight a day while losing weight.
  • Resistance exercise twice a week.
  • Vitamin D 10 micrograms a day from October to March, and all year if you are rarely outdoors.
  • A bone density scan if you have a risk factor: early menopause, a parent who broke a hip, long steroid use, or a BMI under 19 at any point.
  • Any bleeding after the menopause gets a GP appointment.

Paying for your own medicine? The lowest first-order prices today, with delivery included: Mounjaro from £88.00, Wegovy from £44.00, Wegovy pill from £53.00, Foundayo from £46.00.

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Sources

  1. Menopause (NHS)
  2. Menopause: identification and management (NG23) (NICE)
  3. Once-weekly semaglutide in adults with overweight or obesity (STEP 1) (Wilding et al, New England Journal of Medicine, 2021)
  4. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1) (Jastreboff et al, New England Journal of Medicine, 2022)
  5. Bone health and the menopause (Royal Osteoporosis Society)
  6. Vitamin D (NHS)

Sian Anderson

Sian writes the health and nutrition guides on MyGLP. Every clinical claim links to the NHS, NICE, a medical royal college, a regulator or a peer-reviewed paper, and the pages carry no medical advice.