Summary

If the scales have started creeping up in your late 30s or 40s and nothing that used to work is working now, you are not imagining it and it is not a lack of willpower. Perimenopause changes how your body handles insulin, stress, sleep and muscle, and that changes how it stores fat. In this post I explain what keto actually is (a natural metabolic process, not just a diet), why weight loss gets so much harder in perimenopause, which carbs matter and which do not, and what the research does and does not tell us. I also share why I do not start women on strict keto, and answer your questions on carbs, hot flushes, fasting, exercise, timelines and safety.

What is keto, exactly?

Keto is not actually a diet. It is a metabolic process that every one of us has. The name comes from ketones, the fuel molecules your liver makes from fat when your body is burning fat for energy.

Your body can run on two fuels: sugar (glucose) or fat. When sugar is plentiful, it uses that first. When it is not, for example overnight while you sleep or in the long gap between meals, your body turns to its stored fat, and your liver converts some of that fat into ketones that your brain and muscles can use as fuel. That state is called ketosis. Which fuel your body reaches for depends largely on insulin, the hormone that acts like a switch between the two. So you have almost certainly been in and out of mild ketosis many times without knowing it.

Ketones can also be measured, through a blood, breath or urine test, which is one way to see that your body is burning fat. Tools like that can be useful further down the track, but they are not where you start.

So where does the keto diet come in? When people talk about the ketogenic diet, they mean a very low carb, high fat, moderate protein way of eating, usually somewhere between 20 and 50 grams of carbs a day, designed to keep the body in ketosis. Eating that way is one route to burning fat. It is not the only route, and the diet and the process are not the same thing.

Why is it so hard to lose weight during perimenopause?

Perimenopause can start in your late 30s or 40s and last for several years. Estrogen and progesterone begin to fluctuate and decline, and that ripples through your whole system.

Estrogen helps your cells respond to insulin, so as it drops, many women become less insulin sensitive. The same meal can lead to a bigger, longer insulin rise. Fat tends to shift towards the middle. Sleep gets broken, stress hormones climb, and we naturally lose muscle as we age, which slows the metabolism further.

That is a lot of moving parts, and "eat less, move more" only addresses one of them.

My take: So many women come to me having done everything "right". The tracking, the extra cardio, the smaller portions. Then they blame themselves when it stops working. Please hear me on this: your body is not broken and you are not failing. The rules changed, and nobody told you.

Should you avoid carbs during perimenopause?

Not all of them. What matters is the type of carb.

Refined and ultra-processed carbs like white bread, pastries, sweets and most packaged snacks digest quickly and push insulin up fast. Whole food carbs like vegetables, legumes, whole grains and fruit digest more slowly, so the rise in insulin is gentler.

Cutting every carb overnight is not necessary for most women, and in perimenopause it can backfire. Some women find that going very low carb, very fast, while their body is already under hormonal stress leaves them exhausted, wired at night and more frazzled, not less.

Is keto good for perimenopause?

The honest answer is that research on keto specifically in perimenopausal women is limited, so anyone promising you a guaranteed result is getting ahead of the evidence.

What we can say is that the reasoning makes sense. Perimenopause can make your body less responsive to insulin, and eating very low carb takes some of the pressure off that. Some women report fewer cravings, steadier energy and less of that constant hunger once they are running on fat.

There are downsides too. Strict keto is hard to sustain, the first couple of weeks can feel rough, and doing it on top of under-eating, hard training or long fasts can pile stress onto a body that is already juggling a lot.

My take: My first ever diet was Atkins, a very low carb approach. My husband and I did it together and it worked. I still abandoned it, because I did not believe I could eat that way forever, and I did not yet understand why it had worked. That experience is a big part of why I do not start women on strict keto now. I would rather help the body become metabolically flexible, able to switch between sugar and fat again, without the crash that comes from cutting too hard, too fast. Keto can be a useful tool for some women further down the track. I just do not think it is the starting line.

Can the keto diet help with weight loss during perimenopause?

It can, for some women, and it helps to understand why. When a way of eating settles your hunger and steadies your energy, sticking with it stops feeling like a battle, and your body has a chance to respond. That is why two women can eat quite differently and both see their body start to change.

It also explains why keto so often fails when it becomes another form of restriction. If you are white-knuckling a plan, tracking everything and feeling deprived, your stress hormones climb and you are back to fighting your own physiology. Long term results come from working with your body, not against it.

Frequently asked questions

How many carbs should I eat during perimenopause?

There is no single number that suits every woman. It depends on your insulin sensitivity, your activity, your stress load and how your body responds. Rather than chasing a target, start by looking at the quality of your carbs and how you feel after you eat them.

Can keto help with hot flushes and other perimenopause symptoms?

Some women say they feel better with steadier blood sugar, including more even energy and mood. The evidence is limited, so I would not promise it. If symptoms are affecting your quality of life, a conversation with your GP is worth having.

Can I do keto and intermittent fasting together in perimenopause?

I would not start there. Stacking several stressors on the body at once is a fast way to feel worse, not better. Build the foundations first and layer things on gradually. That gentle, one step at a time approach is how the 21 Day Kickstarter is built.

Do I need to exercise more to lose weight in perimenopause?

Not at first. More exercise is not the first step, and piling on extra cardio while your body is still running mostly on sugar can burn muscle instead of fat. First, you want your body able to fuel your workouts with fat, not muscle. Once that is in place, zone 2 training is a great place to start, along with strength training. Zone 2 is a steady pace where you could still hold a conversation, like a brisk walk. Strength training matters because holding on to muscle protects your metabolism as your hormones shift.

How long does it take to lose weight on keto during perimenopause?

It varies from woman to woman, so I would rather not give you a timeline. I look at how your clothes fit and how steady you feel, not just the scale.

Is keto safe during perimenopause?

For many healthy women a well-planned lower carb approach is fine, but it is not right for everyone. If you take medication, especially for diabetes or blood pressure, or you have an existing health condition, please talk to your GP before making big changes to how you eat. Keto is also not suitable if you are pregnant or breastfeeding, and if you have a history of disordered eating, any restrictive approach is worth talking through with a professional first.

Want to go further?

If you have read this far, you are probably tired of being told it is a willpower problem. It is not. It is metabolic, and it is fixable. I'm a health coach who helps women, 35+, lose weight the metabolic way.

Here is a free guide with 3 practical steps you can start right now:

Making Sense of Weight Loss - Free Practical Guide

No quick fixes | Long term results | Real whole food 🌻

Yours in health,

Emma