Food Allergies Vs Food Intolerances

Posted by Michelle on May 19, 2014

Do food allergies make you fat?  That’s a great question and the answer depends on who you ask.

The theory goes: a specific food allergy or allergies prevents someone from losing weight and causes all sorts of awful symptoms.  Diet plans based on this call for dropping a certain food (or in some cases foods) -- so you can lose the weight once and for all.

It’s incorrect to say food allergies are making you fat.  Technically it’s not a food allergy.  It’s a food intolerance in question.  Here a few medical definitions you need to know:

food allergy is an abnormal response to a food triggered by the body’s immune system. When the body has an adverse reaction to food it produces an antibody called immunoglobulin E (IgE). There are several types of immune responses to allergens. The response may be mild like a rash or (in rare cases) it can be associated with a life threatening reaction called anaphylaxis.

A so-called food intolerance causes a wide variety symptoms: everything from bloating, to headaches, and indigestion, but it is not a food allergy.  It is not life threatening.  The most common example of this is lactose intolerance.

From this point forward, I am going to use the correct term: food intolerance.  But realize proponents of elimination diet plans often use the incorrect term: food allergy.  They are not synonymous and you are being misled when they use it.

There is no way to trace back the mainstream popularity of diet plans based on the concept of food intolerances, but Dr. Mark Hyman made a contribution.  He believes the wrong foods make you inflamed, and then the inflammation causes obesity. He even appeared on the Dr. Oz show, where he received support and endorsement for his theories.  More recently someone named JJ Virgin wrote a book and diet plan about food intolerances. Her beliefs and diet recommendations are very similar to Dr. Mark Hyman.  She advocates dropping eggs, dairy, gluten, soy, peanuts, corn, and yeast for a period of at least 21 days. 

Dr. Hyman cites two studies from 2007 to back up his position: one in humans and one in mice. However, you can’t make conclusions about human health based on animal studies.  Animal models do not adequately represent clinical disease.  His evidence in humans comes from a study of children who were already overweight.  He claims their blood work showed high inflammation, whereas normal weight children did not, making the connection that inflammation causes obesity. Scientists really don’t know what happens in humans. And, there is plenty of research that shows those inflammatory molecules might be produced after someone becomes obese, in response to becoming obese—not before. 

Besides the lack of scientific evidence in favor of elimination diets, there is no way proven way to test for food intolerances that might make someone “inflamed”.

Immuglobulin E testing is used to diagnose food allergies.  If your body has an immune reaction to a food or substance, your body sees that item as an invader and will produce IgE in defense.  The body causes the symptoms associated with food allergies as part of that defense.

Doctors who believe in food inflammation use something called immuglobulin G (IgG) testing. The test is also looking for an immune reaction in the body.  Proponents of IgG testing say a positive test indicates your body has intolerance to a certain food. 

A larger portion of the medical community believes the presence of IgG actually indicates your body’s tolerance to the food, not intolerance. So if that's true... why do people lose weight on elimination diets?

Let’s take a look at JJ Virgin’s plan again.  What are you left with when you drop all of her foods: eggs, dairy, soy, yeast, peanuts, corn, gluten? Basically you can eat meat, vegetables, fruits, and nuts. You can’t eat anything processed because many of those seven items are in a lot of packaged foods.  Of course you are going to lose weight.  It is very low carb by nature. It is difficult to over eat those items unless you take a spoon to a jar of almond butter. When you lose weight you experience all those wonderful effects that Virgin touts in her book because weight loss in general causes positive changes.  Even a 10% reduction in weight causes a dramatic change in your body, regardless of how you lose that weight.

There is no correlation that proves eliminating those foods causes weight loss because your body never tolerated them.  In eliminating all seven foods, you are automatically reducing your food choices and are forced to eat a low calorie and low carb.

There are medical circumstances when you should eliminate foods.  A few of those include:

  • If you have an allergy to a food (like peanuts) that causes an IgE mediated reaction, do not eat peanuts.
  • If you have an allergy to dairy or medically diagnosed lactose intolerance avoid it or choose lactose free dairy.
  • If you have medically diagnosed Celiac Disease, avoid gluten.

This article will be updated* as new research becomes available in favor of either side of this issue, if you want to receive those updates and other articles, don't forget to like us on Facebook.

*Originally written on September 24, 2013.  Update May 19, 2014.



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