Why Do I Feel Dizzy, Giddy or Light-Headed After Eating?

Why Do I Feel Dizzy, Giddy or Light-Headed After Eating?

By Dr Joe

After eating dizziness and light headedness appears to be a problem that afflicts a lot of people. So much so that I now get queries in my inbox regarding the problem of feeling giddy, dizzy or light-headed after eating a meal.

I admire people who like to make quantum leaps in searching for the truth regarding their health. These people reject the good in favour of the great. I like the camaraderie that the internet sometimes generates.

after eating dizziness

I like the fact that I can sharpen my mind about stuff that I never thought of as being popular health concerns. Draw my attention to such concerns and I have no choice but to respond to the clarion call.

As they say iron sharpens iron when you are surrounded by lovely and inquisitive folks. It’s one way to keep the golden grey matter active.

That’s how I got to put this piece together because I was prompted by some of my readers to say something about feeling giddy after eating.

The last of the queries came from Peter (not his real name) and I shall reproduce his question which skirts around the problem of after eating giddiness or dizziness and light headedness.

Here we go, Peter. Your words:

“I thought I had hypoglycemia because several medical nurses and doctors have told me I did and that I needed to eat every two hours or so to keep my blood sugar level. But, according to your article, hypoglycemic folks don’t notice the dawn phenomenon I describe below.

I get dizzy immediately after having breakfast. (too much of a blood rise?) I feel good as soon as I get out of bed, with just a hunger feeling, until I eat. Then I am very unstable. The dawn phenomenon in your article says it occurs between 2:00 AM and 8:00 AM and does not have much of an impact on hypoglycemia patients. I don’t eat breakfast until 9:00 AM. By the time I finish eating it may be 9:30 AM.

Would my dizzy disoriented feeling be considered the “dawn phenomenon”? I have never awakened easily all my life. It took me an hour or so to be alert while I was still very active and healthy. But what I am experiencing now is extremely frustrating and debilitating.

I don’t get alert anymore without the dizziness/light headedness. I can’t walk straight, can’t drive and can’t stand very long without getting faint. I have had this problem for the last four years. It came and went. (off and on the first two years, with the help of acupuncture).

Then I must have become immune to acupuncture. It stopped giving me any relief. It is now constant. When I lie down in a supine position I get relief for a short while.

Your article mentions drinking a sweet drink when the blood sugar gets low. I tried that and the dizziness got worse. It seems I am hyperglycemic rather than hypoglycemic. Each time I have had blood drawn and subjected to metabolic evaluation, after fasting, my glucose tests “normal”. My doctor sees me as pre-diabetic.

Is it possible that someone with my symptoms can progress to keto acidosis? That scares me. I hear it can be fatal.

I am confused as to whether I am hypoglycemic or hyperglycemic, neither of which show up in my blood specimens, over and over.

Am I completely headed in the wrong direction? Is there another disease of the pancreas or other parts of the body that would cause my types of symptoms?

Thank you for taking the time to answer my questions and come up with any fresh suggestions or thoughts.”

A little disclaimer here. My advice here is informational and educational not diagnostic. If you are unsure of your symptoms, you may well consult your personal physician. Are we cool? Yep?

Okay, Peter’s problem actually highlights what a lot of folks suffer from (in silence I should add). These people feel giddy, dizzy or light-headed after eating a meal. Some will have a feeling of nausea after eating consistently.

Heck, you are supposed to feel good after eating, not miserable.

First of all, in addressing Peter’s problem, he raised the issue of the dawn phenomenon. Peter says “Would my dizzy disoriented feeling be considered the “dawn phenomenon”? No, Peter it isn’t. I can say your problem is definitely NOT the dawn phenomenon.

The dawn phenomenon is rare occurrence in non-diabetics. Not only that, the dawn phenomenon is not related to food in any way. The dawn phenomenon is a cortisol-related problem that occurs between 2am and 8am. It happens well before you even consider having breakfast. Besides, the dawn phenomenon refers to high blood sugar in relation to cortisol rise. Read about it here, if you may.

feel giddy after eating


People who feel giddy whilst eating or feel lightheaded or dizzy after eating a meal have an issue that may be caused by 7 main culprits:

What can cause after eating dizziness, giddiness, light-headedness or nausea.

  1. After meal low blood pressure (post-prandial hypotension)
  2. Low blood sugar (reactive hypoglycemia)
  3. Heart problems and hardening of blood vessels
  4. Inner ear problems
  5. Thyroid problems
  6. Stress or Anxiety
  7. Medications

Let’s tackle the causes of light-headedness or dizziness after eating one after another briefly.

Low blood pressure (Post Prandial Hypotension)

Dealing with the food you eat is hard work for your body believe it or not. When work is involved then a lot of physiological changes take place that ordinarily you are not aware of. You go on with your life and no one gets to notice. Not even you…ordinarily.

Problem occurs when those physiological adaptations begin to sing out of tune. Feeling dizzy after having your food is one of those situations.

What am I talking about?

Well, the cardiovascular system and your nervous system are called into action to help the digestive system.

To meet the demands of digestion (remember you have just loaded your gut with some grub out of hunger), your cardiovascular system needs to pump more blood into the Gastrointestinal tract. This is to aid digestion, absorption and transportation of nutrients to your body cells where they are needed.

In order for this blood diversion to occur, the other body organs have to “calm down” just a little bit with their blood supply needs. So, vessels to those other organs not directly involved with the digestive process may need to narrow themselves in preference to the widening of the vessels supplying the gut.

This also means your heart needs to beat faster to facilitate these silent events going on. This narrowing of some vessels and widening of the vessels in need of more blood is controlled by the autonomic nervous system (ANS).

We won’t get geeky and get into the nitty gritty of what the autonomic nervous system does but suffice to say, it’s a well-tuned coordination between the circulatory system and the nervous system.

Now whilst all of these events are happening, your blood pressure must stay the same regardless.

When there is poor coordination between the nervous system and the circulatory systems for whatever reason, your blood pressure will not be maintained as it should.

What I am saying here is that, the digestive process provokes a drop in your blood pressure either during the eating process or after you have eaten. This in medical parlance is called post prandial hypotension. Hypotension means low blood pressure. Post prandial hypotension means ‘after eating low blood pressure’.

This ‘after eating drop in blood pressure’ explains symptoms such as after eating dizziness or light-headedness, after eating nausea, after eating fainting episodes, after eating stomach pains and after eating chest pains.

I should add though that after eating chest pains may be due to a heart attack and that’s a lot more serious. Don’t simply assume your symptom of ‘after eating chest pain’ is due to post prandial hypotension. Seek medical help if that is you.

As far as Peter having issues with after food dizziness is concerned, I would suggest he and his medical practitioner exclude after meal low blood pressure.

In particular where Peter says “When I lie down in a supine position I get relief”. Lying down equilibrates blood pressure. The heart doesn’t have to work so hard in pumping blood to your brain when you lie down compared to when you are standing up. Makes sense?

I have also had someone write to me about having dizziness when eating first bite of food. This is likely due to this same blood pressure adaptation problem. Got to remember, the digestive process kicks in from the minute you start chewing your food in the mouth.

Dizziness when eating first bite may seem premature but it happens and it happens because of low blood pressure triggered by the food being chewed and ingested. Same principle.

Low Blood Sugar (After eating low blood sugar)

Another reason someone like Peter is having after food dizziness is low blood sugar. Surprised?

Well, it happens.

Food is supposed to raise your blood sugar but in some people, this rise in blood sugar is a temporary event that is quickly followed by a sudden drop in blood sugar levels.

We call this Reactive hypogylycemia. Searching for the cause of after meal dizziness was the reason, Peter found my website. I wrote in detail about the problem of reactive hypoglycemia here. This the article Peter read.

Essentially the food you eat triggers a huge surge of insulin. This huge surge is followed by a quick response to the very high levels of insulin circulating in the blood.

The response being that the insulin opens the doors of the cells and boom, the glucose in your blood circulation is driven into the cells very quickly. Because that’s what insulin does. It drives sugar into the cells from the blood circulation. High blood insulin means a very efficient blood glucose clear-out.
Too efficient!

The net result of that event is your blood sugar plummets leading to after meal low blood sugar.
A paradox…I know.

Dizziness and light-headedness are some of the symptoms of low blood sugar, hence you feel dizzy after a meal. There are various causes of reactive hypoglycemia or what I call after eating low blood sugar. You may need to be investigated for that to establish exactly why you have it.

Peter in his letter to me, says he has had blood tests done for blood glucose. This is well in order. Why?

Because one of the common cause of reactive hypoglycemia is type 2 diabetes or pre-diabetes. Insulin resistance, in short.

So, Peter has done the right thing about excluding type 2 diabetes and it would appear his glucose results were “normal”. Quotation emphasis his not mine. My deduction from that is his blood glucose results were inconclusive.

If you are someone in Peter’s position, especially if you feel light-headed or dizzy after eating sugar, you need a Standard 75 gm Oral Glucose Tolerance Test or a Mixed Meal Tolerance Test to properly exclude or better still confirm your metabolic status.

Those two tests are probably the best means of resolving any confusion between hypoglycemia and hyperglycemia.

Are you prediabetic? Are you frankly diabetic? Those 2 questions need to be answered properly. This is particularly important in individuals who have dizziness or light-headedness after eating sugary foods or heavily processed carbs.

Although the causes of after meal dizziness may vary, but for folks who feel dizzy or light-headed after eating sugar, the most likely cause is reactive hypoglycemia.

It may actually mean being tested more than once.

Oh yes, Peter, you may need to be tested at least twice. And I mean a full Standardised 75 gm Oral Glucose Tolerance Test, not just Random blood sugar test. Sorry about that but at least you will know where you stand metabolically speaking afterwards.

after eating dizziness


Heart problems and hardening of blood vessels

Your heart is your body’s pumping machine. It pumps blood from the heart for onward distribution to the rest of your body.

Remember, I said earlier on that your heart will need to pump faster and sometimes harder to accommodate the increased blood flow requirement needed by your intestines to digest, absorb and transport nutrients to nourish your body.

For this to happen, the heart needs to pump efficiently and obey orders from the autonomic nervous system. The blood vessels need to be pliable to enable relaxation of their walls or constriction of their walls depending on the task at hand.

If the vessels are hardened, that means they can’t relax very well. This is called atherosclerosis. This means the blood pressure changes essential for the digestive process will not occur as ought to be.

Also, if the heart cannot pump efficiently in response to these digestive needs, blood pressure will be low. Low blood pressure after eating will eventually lead to dizziness or light-headedness after eating.

Inefficiency of the heart pump or hardening of blood vessels may occur together or exclusively. Either way, both heart pumping issues and or hardening of blood vessels (atherosclerosis) can cause after meal dizziness, giddiness or light-headedness.

Inner ear problems

There is a part of the inner ear that contains what we call semi-circular canals. These canals contribute to our sense of balance.


There are 3 semi-circular canals that lead up to one central area called the vestibule. This vestibular area has a nerve called the vestibular nerve which joins another nerve called the cochlear nerve. This conjoined nerve sends signals to the brain where movements and hearing are interpreted.

The cochlear nerve is responsible for hearing, by the way and the vestibular nerve and vestibular system is responsible for balance. The vestibular system senses movements by activating the sensory nerves when you make any movements in particular moving your head in any direction.

Anything that disrupts the smooth functioning of this system will affect your sense of balance either standing up or even sitting down.

Infections of the inner ear by bacteria or a virus and meniere’s disease will cause you to feel dizzy after eating in an indirect way. Also, anything that affects a smooth blood flow to the inner ear, head injury can lead to dizziness following a meal.

Thyroid problems

Thyroid issues be it underactive or overactive thyroid problems can cause dizziness on their own in the absence of a meal challenge. The mechanism is not very clear but dizziness is a recognised symptom of hypothyroidism or hyperthyroidism.

Whether one can blame a malfunction of the thyroid gland to light-headedness after eating is open to question. But I have had people say their dizziness after eating was corrected after they fixed their overactive or underactive thyroid problem.

So, if you work it from first principles, you may conclude that the after eating dizziness encountered by that individual may have been due to the thyroid problem.

feel giddy after eating


Stress and Anxiety

Stress does all sorts of silly damage to our body. Prolonged stress can lead to anxiety-related mental health problems.

One thing I have noticed in my medical career is that when you have anxiety, it can lead to all sorts of symptoms. Some of those symptoms may be difficult to explain, but they happen nonetheless. So, having after eating dizziness or nausea as a result of stress does not come to me as a surprise.

It is tall order to ask people to reduce stress in their lives because stress reduction is not a push-button exercise. But if you can, then by all means do so. Going back to Peter’s situation, I suspect that even though there may be a physical cause to his giddy spells following a meal, I also think there is an anxiety aspect as well.

I say that because as you can tell from Peter’s account above, he found some relief from acupuncture but that relief was short-lasting. Acupuncture is not an evidence-based treatment for after eating dizziness. My theory is that the acupuncture provided a psychological remedy at the time, rather than a physical one. Obviously, the remedial effect faded away over a short time, sadly.

The fact that Peter responded initially to the acupuncture, makes me think there is a psychological component to his light-headedness and giddiness after eating.


Will medications make you feel light-headed after you have eaten? Of course, they can. The problem is worse when you are on a host of medications that may work synergistically together.

Any blood pressure lowering medication can cause you to become dizzy with or without food. I am referring to medications prescribed by your doctor to control hypertension of whatever cause. That’s why your doctor may need to monitor your response to your blood pressure meds both in his office and at home.

Also, prescription meds that will make you pee more often can have the same effect. Meds that enable you pass urine often (what we call diuretics) can shrink your blood volume, causing your blood pressure to drop. This drop in blood pressure can cause you get giddy after eating. Some antihistamines can make you feel dizzy as well.

Those causes listed above are the reason you may feel dizzy or light-headed after you have had your food. You may need a little adjustment to your lifestyle to control or deal with the after eating dizziness problem and of course if the cause is found, the task of solving it becomes easier…a lot easier.

Suggested further reading:
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