Have you ever finished a meal and, not long afterwards, felt that unmistakable wave of heat begin to rise? Perhaps your face and chest become flushed. You start to perspire. You find yourself pulling off a layer while everyone else at the table seems perfectly comfortable. If you’re in perimenopause or menopause, it can be easy to put it down to yet another hot flush. But if you’ve noticed that yours seem to happen around food, you might reasonably wonder: why does eating make me hot?

The interesting thing is, the research doesn’t give us the straightforward answer you might expect.

What is actually happening during a hot flush?

We often talk about hot flushes as though the body has simply become too hot. But what is happening is far more complex. Your hypothalamus, a region within the brain, plays an important role in regulating body temperature. During the menopausal transition, changing estrogen levels can affect the neural pathways involved in this process. Research into the thermoregulation changes that occur during menopause has increasingly focused on a group of neurons known as KNDy neurons. These neurons are sensitive to estrogen and communicate with areas of the hypothalamus involved in temperature regulation.

As estrogen declines, the activity of these neurons changes. This is thought to contribute to the activation of the body’s heat-loss mechanisms, including increased blood flow to the skin and sweating, producing the characteristic rush of heat some women (not all) experience as a hot flush. So while we often describe hot flushes simply as a ‘hormonal symptom’, there is actually a fascinating conversation taking place between your changing hormonal environment, your brain and the systems responsible for regulating body temperature.

So, does eating trigger a hot flush?

You might assume so. After all, eating requires energy. Your body has to digest, absorb and metabolise the nutrients in your meal, which temporarily increases energy expenditure and heat production. It would be easy to join those dots and conclude that the heat generated during digestion is enough to trigger a hot flush in a body whose temperature regulation has become more sensitive. Yet, that’s not what the limited research we have has shown.

In one small study specifically examining dietary intake and hot flushes, researchers monitored symptomatic postmenopausal women around meals. Rather surprisingly, they found that eating was followed by an average hot-flush-free period of around 90 minutes. Hot flushes became more frequent as the length of time between meals increased.

Now, this was a very small study, involving just 10 women in the controlled portion and 21 in the observational portion, so we certainly can’t use it to make sweeping conclusions. But it does challenge the seemingly obvious explanation that eating itself is a driver of hot flushes.

Could blood glucose be part of the picture?

This is where things become particularly interesting. In that same small study, hot flushes tended to occur when blood glucose levels were lower than they were during hot-flush-free periods. The researchers proposed that changes in glucose availability to the brain might be involved. Again, this is a hypothesis rather than something we can consider established. There is, however, broader research suggesting a relationship between vasomotor symptoms and metabolic health, which may begin to explain why some women don’t experience hot flushes at all during their perimenopause transition.

A large study involving more than 3,000 women from the Study of Women’s Health Across the Nation found that women reporting hot flushes and night sweats had higher measures of insulin resistance, even after the researchers accounted for a number of other factors. Importantly, an association is not the same as causation. This research does not tell us that insulin resistance causes hot flushes. Nor does experiencing a hot flush after a meal mean there is something wrong with your blood glucose regulation. What it does tell us is that the relationship between our reproductive hormones, metabolism and temperature regulation may be more interconnected than we once appreciated.

And there is still much more to learn.

What about particular foods?

This is another place where it pays to separate personal experience from established evidence. Spicy foods, alcohol, caffeine and hot drinks are all commonly discussed as potential hot flush triggers. You may have even been advised to eliminate them as a trial to see if this makes a difference for you. And some women absolutely do notice a relationship. But according to the Australasian Menopause Society, while some women identify things such as spicy foods, alcohol, caffeine, hot beverages, warmer environments and stress as triggers, evidence supporting these triggers is lacking. Please don’t let this take away from your personal experience though.

The Menopause Society similarly notes that avoiding commonly cited triggers such as alcohol, caffeine, spicy foods and hot foods has limited solid evidence behind it as a strategy for reducing hot flushes. This doesn’t mean your experience isn’t real if you consistently notice that a glass of wine or a hot curry brings on a flush. It means we shouldn’t assume that everyone needs to remove the same foods or drinks.

Your pattern is worth paying attention to

This is where I come back to something I have encouraged women to do throughout my career: become curious about what your body is communicating. If you regularly experience hot flushes around eating, pay attention to the pattern, before deciding what it means.

• Does it happen after every meal or only particular ones?
• Does it happen immediately after eating, or an hour or two later?
• Does the size or composition of the meal seem to make a difference? For example, if you eat a high fat meal, do you flush but a low fat meal doesn’t bring on the heat? If you eat a vegan meal, does everything stay calm – or not? If you change the ratio between protein foods and vegetables (increasing the veg and decreasing the protein), does this make a difference to your experience of hot flushes?
• Is alcohol or caffeine involved?
• Had you gone a long time without eating beforehand?
• Does it happen more frequently when you’re stressed or underslept?

And is what you’re experiencing actually a hot flush, with a sudden wave of heat, flushing and perhaps sweating, or are you simply noticing that you feel warmer after eating? You might even find it helpful to keep a simple record for a couple of weeks. Not because you need to obsess over every morsel you eat, but because patterns can be difficult to recognise when we are relying on memory alone.

Not all women experience hot flushes across their menopausal transition. And those who do, I hope this helps you dig into what’s driving them, as it’s not always changes in hormones behind the heat.