Twelve hundred calories a day, an app to count everything, no more bread, no more cheese, and some evenings no dinner at all. Three weeks held together by sheer willpower, two kilos gone, then one weekend where it all falls apart. Many women with PMOS know this script by heart, sometimes since their teens. They were told to eat less and move more. They did, often harder than anyone else, and the weight came back with cycles as irregular as ever.
Their willpower is not the problem. The method is.
A body that feels under threat holds on to everything
PMOS is first a story about insulin. In a large share of the women affected, the cells respond poorly to it, the pancreas makes more, and that excess pushes the ovaries to produce androgens. I explained this loop in the article on the new name.
A harsh restriction adds stress to ground that is already tense. In the United States, 121 women followed one of four instructions for three weeks. Count calories or not, eat 1,200 kcal a day or eat normally. The women eating 1,200 kcal saw their total cortisol output rise. The ones counting everything reported feeling more stressed (Tomiyama et al., 2010).
These women did not have PMOS. But cortisol raises blood sugar, and insulin follows. When insulin is already too high, that is exactly the direction you want to avoid. Stress also scrambles the signals the brain sends to the ovaries, and ovulation pays for it.
Then there is muscle. A brutal cut costs you some, and muscle is where sugar gets stored and burned. Less muscle means a body that needs more insulin to handle the same meal.
Fragile ground for dieting
Eating disorders are more common with this syndrome. A meta-analysis published in 2024 to inform the international guideline pooled 20 studies, with nearly 29,000 women with the condition and more than 250,000 without. Women with PMOS had an eating disorder clearly more often, binge eating disorder and bulimia in particular, whatever their weight (Cooney et al., 2024).
Deprive yourself, crack, blame yourself, start again on Monday. That cycle throws hunger off and ends up worsening the very insulin resistance it was meant to fix. This is why I never put a woman with PMOS on a harsh diet. We start by eating enough, simple food, at regular times. Weight loss comes afterwards, when it is useful.
It takes far less than you think
In London, in the early 1990s, a team followed 24 women with PMOS and excess weight for six to seven months. Thirteen lost more than 5% of their weight. In them, fasting insulin dropped sharply, the protein that binds testosterone in the blood went up, and free testosterone went down. Of the eleven with disrupted cycles, nine saw their periods become more regular or got pregnant. In the women who lost less than 5%, almost nothing had moved (Kiddy et al., 1992).
The diet in that study was 1,000 kcal a day, and I would not recommend it to anyone. What matters is the threshold. For a woman weighing 80 kilos, 5 to 10% means 4 to 8 kilos. Not 20.
In Adelaide, Australia, 13 women with excess weight who no longer ovulated followed a weekly programme on food and exercise for six months. They lost 6.3 kg on average. Twelve started ovulating again, and eleven became pregnant, five of them without any treatment (Clark et al., 1995).
Ovulation comes back when insulin comes down
The same Adelaide team wanted to understand what made the difference. Eighteen women with PMOS, excess weight and no ovulation followed a six-month programme that did not aim for rapid weight loss. The women who started ovulating again had lost 11% of their belly fat. Their insulin sensitivity had improved by 71%, and their fasting insulin had dropped by a third. In the women whose ovulation did not return, none of these numbers had really changed (Huber-Buchholz et al., 1999).
So the turning point does not come from the number on the scale. It comes from insulin going down. A moderate deficit, around 10% of your needs, gives far better results over time than a brutal cut. The body keeps its muscle, metabolism does not collapse, and hunger stays manageable.
Eat enough, and move
A small deficit has one huge advantage. You can stick to it. Full meals at set times, hunger to guide the rest, and no constant grazing, which keeps insulin high. What goes on the plate to calm insulin is covered in the PMOS diet article. Breakfast, which so many women skip to "save" calories, has its own article, what to eat for breakfast with PMOS.
Daily fasting has no place here. Skipping breakfast every day weakens muscle and restarts the spiral of deprivation and overcompensation.
Movement does part of the job that restriction cannot. Ten to fifteen minutes of walking after lunch and dinner bring blood sugar down clearly. Two to three strength sessions a week make the body more sensitive to insulin. Hours of cardio on too little food do the opposite and push cortisol up.
If you are slim, the question is different. Losing weight is not the goal. The point is to eat enough protein, build muscle and calm insulin through your plate and through movement.
The women who come to me after years of dieting are often afraid of eating more. Yet that is where everything starts. Your body needs to feel safe before it lets go of weight and restarts its cycles.
This article is for information only and does not replace medical advice.