The Secret Cause of Food Intolerances

Chances are that before someone started spouting off that "carbs are the devil," they were, at some point in their life, able to handle decent amounts of carbohydrates without suffering any of the alleged negative health effects.

Over the years I've amassed a number of stories where someone could pretty much eat anything they wanted but then decided to adopt a fad diet. Once they begin their new diet, though, they begin experiencing digestion issues. These could include bloating, headaches, acid reflux, or lethargy after eating a meal.

When researching their symptoms, they're likely told that this is all part of the "detox" or "adaptation phase" of the diet. This eventually leads to wasted hours researching exotic probiotics, deficiencies, elimination diets, and proper meal timing to alleviate their digestion issues.

Now, some will claim, "Being sensitive to food is just part of getting older – our bodies can't handle the same foods like when we were younger." Could be. But I've known many picky eaters that swear they have "x" food allergy who eventually fall off their diet bandwagon and eat the supposedly offending food(s), at which point they magically revert back to their 8th grade metabolism.

And that is exactly what's at the heart of the issue. Among its many nuances, our metabolism has the ability to be altered by what and how much food we choose to consume. Both are of equal importance.

Health nuts and yo-yo dieters both have starvation in common. That might sound a little drastic but that's what your body senses when its baseline metabolic set point is altered from a reduction in calories, nutrients, or special food rules that cause both.

All have the potential to trigger the same physiological reaction. The body may begin to accommodate to your caloric deficit or your new diet by slowing down your metabolism. The fact is, your body doesn't like change (except possibly when it's necessary).

So when you go on a diet, expect the body to adapt to a change in metabolism. And most likely this metabolism will be slower and less efficient than it was before. This can produce symptoms such as bloating, constipation, feeling cold, low blood sugar, lethargy, etc.

So don't blame McDonald's for a hamburger that doesn't sit as well as it did when you where seven. YOU might have something to do with it.

Vegan Diet

Ditching animal products can produce a number of metabolic adaptations. One in particular is changing the acid content in the stomach. Increasing the amount of veggies and decreasing the amount of meat can push the stomach into a more alkaline environment, which can cause a reduction in stomach acids (hypochlorhydia) that break down acidic foods.

If you get acid reflux when you cheat on your diet with a burger and proclaim "meat is not right for me," it may have been you who created the issue. You suspect it's too much acid that's burning a hole in your gut, but in most cases it's probably low acid from your previously alkaline diet that's to blame.

Low Fat

You've been avoiding most fats and then you abruptly introduce a higher amount of fat to your diet. Of course you're going to get queasy, even if that amount of fat is something you used to tolerate quite well.

One of many adaptations from a low-fat diet is the functioning of your gallbladder. Since it's primary function is the digestion of fatty foods, avoiding fat creates a "use it or lose it" response. Re-introducing fats creates confusion, in addition to possibly putting you at a higher risk of gallstones.

Low Carb or Keto

A paper published in the British Medical Journal documents a common phenomenon in our nutritional culture. The researchers describe three patients who adopted a low-carb diet because of an assumed carbohydrate "allergy."

Their self-imposed low-carb diet seemed to alleviate symptoms that were brought on by carbohydrates. The researchers concluded the likely cause of these symptoms was indeed the carbs, which led to late hypoglycemia (low blood sugar), but this is exactly what happens when you restrict carbohydrates.

In a splendid display of confirmation bias, the patients lost weight and further restricted their diets to reduce their symptoms because their tolerance to carbs became progressively worse.

Sound familiar? The researchers pointed out a very well known but underrated effect of low energy diets: They lead to "abnormalities of carbohydrate metabolism."

If you don't have a known, diagnosed medical condition, consider getting back to having a healthy relationship with food by eating a balanced diet. This means listening to your body and not what your diet tracker app or diet guru tells you.

Not feeding your body properly to meet your lifestyle is often manifested by negative symptoms that many times seem like food allergies or intolerances. If, however, your "special" diet is producing positive health benefits and you're able to adhere to it long term, by all means keep at it.

As always, go to your doctor when starting any new diet.

1. Bethune CA et al. Physiological effects of starvation interpreted as food allergy. BMJ 1999;319:304.