Weight Loss Resistance in Menopause: What the Research Is Testing

Plenty of women hit their mid-forties and find the approach that used to work reliably has stopped delivering. Same training, same discipline around food, far less to show for it. That experience tends to get waved away with some version of "you must be eating more than you think." Sometimes that is exactly what's happening. But there is now research being done specifically on the women for whom it might not be the case.

Weight loss resistance is about the size of the deficit, not whether deficits work

Weight loss resistance can be defined by the body no longer responding the way it normally would to a diet intervention, and research in this space is sparse, particularly in perimenopausal and postmenopausal women leading a fitness lifestyle. Anecdotal reports, however, are becoming more frequent, and this has led Bill Campbell, professor of exercise science at the University of South Florida, to formally investigate it. A woman who would drop 10 pounds at a given calorie deficit at 35 might now drop three at the same intake and the same training load. Or she has to diet considerably harder than she ever did before to get the result she used to get easily.

Just to be upfront: this is a very different claim from "calories stop counting in menopause." The same diet rules apply at this time of life: if you restrict calories, you will lose fat. There is no study where a deficit was prescribed and fat loss failed to occur. The open question is whether the menopause transition changes how much restriction is required, and whether that shift is due to menopause or simply to aging, which is happening at the same time. Nobody can fully separate those two, because you can't hold one still while you test the other.

Is it just underreporting of calories?

Underreporting of food intake is thoroughly documented, and it explains most people who say they can't lose weight while not tracking at all. Being 300 to 500 calories out from what you think you're eating is common, and it is enough to erase a deficit entirely. This is true of both the general population and of nutrition professionals: tracking requires a level of rigour that not many people possess. Practice in this skill is required in order to do it properly.

Prof Campbell’s research is testing the menopause question, recruiting resistance-trained women who already track, comparing premenopausal women to those in peri or early postmenopause on the same 25 percent calorie deficit with protein set at 1.6 g per kg. The only intervention is the drop in calories. If a difference in fat loss shows up between those groups, it will be hard to explain away with tracking accuracy.

A practical take home of this for anyone who feels they aren’t seeing their effort reflected in their results: weigh your food properly for two or three weeks before concluding anything about your metabolism.

Four aggressive days, then get out

If a woman does require a more aggressive approach but is concerned with crash dieting, Dr Campbell’s case series on his fat loss protocol may offer some relief. Crash diets fail because they run longer than they should, they are low in protein, muscle loss is inevitable and appetite goes through the roof. Regain is not only inevitable, it is worse than the starting point. Dr Campbell's lab asked the question of whether you could be aggressive for long enough to strip fat but not long enough to start losing lean tissue.

Their protocol was two weeks establishing true maintenance calories, then four days at 1.6 g protein per kg with only trace carbohydrate and fat, which lands most women between 300 and 500 calories a day, plus six hours of walking daily. Three days back at maintenance, then 30 days eating however they liked. Clearly aggressive!

In the published preliminary analysis of seven resistance-trained women averaging 55 years, body mass dropped 1.73 kg over the first seven days, with 1.53 kg of that coming from fat and only 0.2 kg from fat-free mass. Thirty days later, eating freely, their follow up revealed a maintenance of these results, and net fat loss had extended to 2.23 kg and fat-free mass was slightly up.

While it might be tempting to do several rounds of this, it is worth noting that one participant liked it enough to run the four days again during the follow-up month, ending up with eight aggressive days out of 37, and she lost over a kilogram of lean mass. Dr Campbell warns that the brevity is the mechanism. Repeat it too soon and you've simply built yourself a crash diet with extra steps. This was just one small study but it is forming part of the bigger evidence base for what might work if a woman experiences weight loss resistance in this stage of life.

Further reading: Shannahan L, Muniz M, Silva Ramirez VV, Holtje J, Paz J, Shelton G, Campbell BI. Effect of a rapid fat loss protocol on body composition and weight regain in midlife females: a case series study preliminary analysis. Journal of the International Society of Sports Nutrition (2025). https://doi.org/10.1080/15502783.2025.2550190

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