The calcount Team
What causes a Hot Flash after Eating

What causes a Hot Flush after Eating?

One of our members asked us what causes a hot flush, or flash, after eating? The question came through our contact form, where we invite readers to send in any topics they’d like to see us research. So, we spent a few hours to learn the causes of hot flushes that are not menopause, here is a summary of what we found:

What is a Hot Flush?

Hypothalamus causes hot flashes

For those who have not experienced one, it can be hard to explain. Basically, it feels the way it is named: a rush of hotness that crashes through the body like a wave of boiling water. It is a sudden uncomfortable sensation of body heat, usually resulting in quick sweats and accompanied by heart palpitations and flushed skin. Hot Flashes are usually caused by hormonal changes in both women and men which affect the brain part (hypothalamus) which controls body temperature. Body temperature rises, blood vessels quickly dilate, and stress responses are stimulated.

Not Menopause, not Andropause

Hot flushes are usually associated with menopause or andropause when hormonal changes in ageing people trigger the hypothalamus to misbehave. However, the hot flashes we are writing about today are caused by neither menopause nor andropause.

Here’s an extract from the question we received:

“… my face, neck, chest and upper arms are suddenly hot and sweat pops out uncontrollably. It does not happen every time I eat but it only happens after I eat and it does not seem to be related to what I eat because sometimes its dairy meat or salad or bread. I am a bit concerned it might be hot flushes but I am still young and definitely not near menopause and besides being a bit overweight I am generally very healthy. Is there a particular food I should be concerned about?”

Now before we go any further, remember that the calcount team is not in any way shape or form medically qualified to offer health advice. We’re just sharing the results of our personal research so please consult your doctor before you take any action because of this post.

5 Triggers can Cause a Hot Flash after Eating

Unfortunately, the exact cause of a hot flush experienced after eating is unknown. The problem is that the phenomenon is hard to study because experiments and measurements would need to be made at exactly the moment of the hot flush in a controlled environment. This is difficult to do for an individual, let alone a controlled scientifically determined cohort. At this stage, the best we can do is narrow causes down to 6 triggers which have been somewhat determined:

Gustatory Sweating

Gustatory sweating, also known as Frey’s Syndrome is a distressing condition caused by nerve damage which affects people who have a malfunctioning parotid gland. The parotid gland is supposed to produce saliva when the nervous system signals that food is about to be chewed. However, for people suffering from Gustatory Sweating, the nerve signals go to sweat glands instead, so that sweat is produced rather than saliva. For some people, this sudden sweating is distressing and feels like a hot flush. Even thinking about food can trigger sudden sweats on the face, neck, and head.

The cause of Gustatory Sweating is usually nerve damage, which in turn is usually caused by diabetes mellitus, facial injuries (for example, through surgery), tumour growth, or a viral infection like shingles.

Unfortunately, nothing can be done to repair this nerve damage at this stage of medical advancement. The best that doctors can do is inject a type of Botox to stop the sweat glands from working temporarily.

Food Allergy and Intolerance

Whilst it is not yet well understood, there is evidence that food allergies and intolerances can cause hot flushes for some people.  The hypothesis is that the body releases a stress hormone (cortisol) when undergoing an allergic reaction. This creates a hormonal imbalance which, similarly to menopause and andropause, interferes with the hypothalamus to cause a hot flash. The frustrating aspect of this hot flush trigger is that it is difficult to pinpoint because it does not happen every time the allergen is eaten. Even if the sufferer knows what they are allergic to, their internal hormonal balance influences whether a hot flush will occur.

Common avoidable food ingredients which are known to set off hot flushes in some people are: caffeine, sulphites, monosodium glutamate, and alcohol.

Hypoglycaemia

We mentioned earlier on in this article that diabetes can cause nerve damage which leads to Gustatory Sweating, but the disease has another aspect which can trigger hot flashes. Sometimes, after eating a sugary meal, the body releases a large amount of insulin into the blood. Insulin is a hormone which works to regulate the amount of sugar (glucose) in the bloodstream. The insulin spike causes low blood sugar, which in turn pushes the stress hormone button, which leads to a hot flush. This low blood sugar condition is known as hypoglycemia and is most associated with diabetes.

As you might expect, treatments to control diabetes can alleviate hot flushes after eating.

Vasodilating Foods

Some foods contain chemicals which cause blood vessels to open wide to allow blood to flow through quickly. This opening of blood vessels is known as vasodilation and chemicals which cause vasodilation are called vasodilators. When blood rushes through widened blood vessels near the skin, flushing occurs. The vasodilators can also stimulate temperature sensory cells in the skin, causing a sensation of heat. This hot flushing sensation can then trigger stress hormones and a full-blown hot flash might occur.

Normally, vasodilating foods are a good choice because they help circulation, but if they are triggering hot flushes you might want to reduce them from your diet. Common vasodilator containing foods are chilli peppers, capsicums, alcohol, chocolate, and garlic. You can read our in-depth article on garlic here.

Hot Food and Drink

Hot Food causes Hot Flush

Unfortunately, some people are overly sensitive to food temperature. A hot mug of tea might be just what you feel like having after coming in from a cold day outdoors, but it could trigger a hot flush. In the same way that vasodilating chemicals widen blood vessels, so does heat from any source. Hot weather, a hot bath, the sauna, or a bowl of steaming noodle soup, all cause vasodilation. As we wrote in the previous paragraph, vasodilation can start a hormonal chain reaction which results in the dreaded hot flash.

This cause of hot flushes after eating is the easiest to avoid; simply let your food and drink cool to a manageable temperature before you eat.

Conclusion – What Causes a Hot Flush after Eating

There are at least 5 possible causes of a hot flush after eating, most related to how the hypothalamus controls body temperature. Whilst there is not much that can be done about Gustatory Sweating, the other causes like Food Allergies, Hypoglycemia, and Vasodilating Foods can be addressed somewhat effectively. Remember that hormonal balance is key to the proper function of the hypothalamus, so try to reduce stress and avoid foods which irritate.

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