Do Bioidentical Hormones Help You Lose Weight? What the Data Show

No, not directly. Menopausal hormone therapy is weight-neutral on average and it slows the build-up of abdominal fat. Progesterone can bloat, but it does not add fat. Testosterone changes body composition, sometimes without moving the scale at all. And when weight loss is needed, it comes from a metabolic plan, with a GLP-1 agonist when the bloodwork supports it, alongside hormone therapy rather than instead of it.

Here are the data behind each of those sentences, and how we apply them at Manus Solis.

Why weight changes at menopause

The menopause transition raises fat mass and lowers lean mass, which lowers the basal metabolic rate. According to The Menopause Society’s 2022 position statement, the average weight gain in midlife, after adjusting for body size and ethnicity, is about 1.5 pounds a year, and fat distribution shifts toward the abdomen independently of age, total body fat and activity level. About two years after the final period, the weight curve flattens.

Two things follow. Midlife weight gain is mostly a matter of age, muscle mass and metabolism, not estrogen alone. And the fat that settles in is the kind that matters most for health: visceral fat, around the organs.

Estradiol and progesterone: neutral on the scale, favourable at the waist

The trials are clear on one point. The same position statement summarizes the evidence this way: estrogen-progestogen therapy “either has no effect on weight or is associated with less weight gain” in the women who use it. In the Women’s Health Initiative, women randomized to hormone therapy had no significant difference in weight compared with placebo, but their waist circumference increased less over the first three years. The Society concludes that hormone therapy “may help attenuate abdominal adipose accumulation and weight gain” during the transition, while noting that the effect is small.

In other words, estradiol is not a weight-loss drug, and a clinic that sells it as one is misleading you. What it does is remove one of the drivers of abdominal redistribution, improve the sleep and hot flashes that undermine training and appetite, and reduce the risk of new-onset type 2 diabetes, an effect the position statement calls significant without making it an approved indication.

Progesterone bloats; it does not add fat

Searches for “Prometrium and weight gain” are common, and the answer deserves precision. Micronized progesterone can cause bloating and fluid retention in the first weeks, and it makes you drowsy, which is why it is taken at night. What you see on the scale then is water and a slower gut, not fat. In most women it settles. When it does not, we adjust the dose, the timing or the route rather than remove the hormone that protects the endometrium and sleep.

Testosterone changes body composition

In men, testosterone is the hormone whose effect on the body is best measured. A meta-analysis of 32 observational studies covering 4,513 men (Corona et al., Journal of Endocrinological Investigation, 2016) found, at 24 months of treatment, an average weight reduction of 3.5 kg and a waist reduction of 6.2 cm, with fat mass down, lean mass up, and fasting glucose and insulin resistance improved. The authors note that the weight effect needs confirmation in a randomized trial designed for it.

An Australian randomized trial (Ng Tang Fui et al., BMC Medicine, 2016) shows what happens when testosterone is added to a diet. One hundred obese men followed ten weeks of a very low energy diet and 46 weeks of maintenance, with testosterone or placebo. Both groups lost the same weight. But the testosterone group lost 2.9 kg more fat, more visceral fat, and kept 3.4 kg more lean mass. Men on placebo lost fat and muscle; men on testosterone lost almost only fat.

That is why we talk about body composition rather than weight. A man who restores his testosterone may see the number on the scale barely move while his waist recedes and his strength returns. In women, the data on testosterone and body composition are thinner, and we do not prescribe testosterone for the purpose of losing weight.

What actually drives weight loss

When a patient arrives with a weight goal, the bloodwork starts before the first prescription: fasting insulin and glucose, HbA1c, lipids and a full thyroid panel, on top of the sex hormones. Insulin resistance or an undertreated thyroid often explains a good part of the problem, and no bioidentical hormone makes up for either one left unaddressed.

The plan that follows has four parts: enough protein, resistance training to rebuild the lean mass that midlife takes away, repaired sleep, and, when the metabolic bloodwork supports it, a GLP-1 agonist prescribed alongside hormone therapy. The logic of the Australian trial applies here too: rapid weight loss burns muscle along with fat, and hormone therapy, with training, is what protects lean mass while the weight comes down.

When should you stop bioidentical hormones?

There is no fixed age. The Menopause Society writes that “an arbitrary age-based stopping rule is not clinically appropriate” and that hormone therapy “does not need to be routinely discontinued in women aged older than 60 or 65 years.” The decision is made each year, on symptoms, bone density, each woman’s own cardiovascular and breast risk, and on what she wants. Weight is not a reason to stop; it is a reason to revisit the metabolic plan.

How it works at Manus Solis

Consultations are virtual and are for patients located in Ontario at the time of the visit. Vis Viva Onboarding includes the initial assessment, the laboratory requisition, the review of your bloodwork, the prescription and the follow-up visit at 4 to 6 weeks where the first dose is adjusted. We prescribe Health Canada-approved bioidentical products, such as estradiol gel and patches and micronized progesterone, as well as compounded preparations where they meet the need better. The full cost picture, including what OHIP and private plans cover, is in Is BHRT Covered by OHIP?.

Continue Reading

• Is BHRT Covered by OHIP? What Ontario Patients Need to Know About Costs
• How Insulin Resistance Is Quietly Destroying Your Testosterone
• Progesterone: The Most Underrated Hormone in Women’s Health

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Dr. Handsun Xiao is a McGill trained physician (MD, CCFP) practicing functional medicine and bioidentical hormone therapy, with virtual consultations available to patients across Ontario. He completed BHRT training through WorldLink Medical and the IFM AFMCP program. Manus Solis offers physician led BHRT consultations, with Health Canada-approved products and compounded preparations from its Ontario pharmacy partner, Trutina. To learn more or book a virtual consultation, visit manussolis.ca.