Can Food Allergies Cause Weight Gain?

Digestive Disorders Nutrition Weight Loss

Can Food Allergies Cause Weight Gain?It’s estimated that a majority of the adult U.S population suffers from mysterious symptoms — like headaches, digestive problems, body aches, insomnia, and even weight gain. What makes them mysterious is that they often go undiagnosed. This can be frustrating for both you and your doctor. But take heart: Researchers have discovered what might be behind some of those symptoms — food! Studies show a possible connection between food allergies, weight gain, and increased inflammation.

How Could Food Cause Mysterious Symptoms?

Your body can react to food as a foreign invader. Just like when your immune system attacks viruses and bacteria, food can also become a target of immune attack. And when the immune system revs up against what it perceives as foreign invaders, all sorts of symptoms can develop. There are two types of immune attacks: immediate and delayed. An immediate attack is the true food allergy and can be life-threatening. It occurs when certain foods trigger the immune system to release large amounts of the chemical histamine. When large amounts of histamine flood the body, a potentially life-threatening condition called anaphylaxis can occur. This is not what is being referred to here. Instead, the focus is a delayed attack — an immune response that’s not as aggressive as an immediate response. This is a low-grade, smoldering attack that is categorized as a food sensitivity and not a true allergy. Some researchers believe that this is what’s behind many people’s mysterious symptoms, including weight gain.

The Effects of Delayed, Low-level Immune Attacks

This chronic, low-level immune system activation is mediated through immunoglobulin G (IgG), an antibody found in all bodily fluids which protects against infections. Inflammatory substances are produced in response to IgG antibodies at the level of the gut wall. These inflammatory factors generate free radicals that interact at the local level of the gut wall to enhance the ability of molecules in our gut to be absorbed intact through the gut wall and enter the bloodstream. These molecules can then further cause low-level inflammation at the tissue level, with fluid retention a common sign. In fact, fluid retention and the inability to lose weight despite dieting are often-overlooked signs of chronic, low-level immune system activation and associated inflammation due to undiagnosed food sensitivity. Scientific research shows that food sensitivity and associated anti-food IgG antibodies play an underappreciated but important role in weight management. For example, a human clinical study in the journal Experimental and Clinical Endocrinology & Diabetes compared anti-food IgG antibodies and a pro-inflammatory factor known as C-reactive protein (CRP) in obese and normal weight subjects.1 Researchers found that the level of inflammation as measured by CRP in obese volunteers was 200% higher than the normal weight study volunteers. Furthermore, anti-food IgG antibodies were dramatically different between the two groups. Additionally, the mean anti-food IgG level in obese subjects was 141% higher than normal weight subjects.1 Clearly, identifying food sensitivities and avoiding those foods can play an important role in your weight management plan.

Can a Simple Finger Stick Test Hold All the Answers?

Unfortunately, identifying which foods may be causing your chronic inflammation and weight gain can be like trying to find a needle in a haystack. There are many food allergies and sensitivities. And until recently, the available detection methods have been rudimentary at best. The good news is that advances in individualized blood testing now enable you and your doctor to zero in on the compounds that may be causing your problem. Simple tests are available for measuring your sensitivity to certain foods from an antibody-mediated immune response. The antibody measured in these tests is IgG. It requires a “finger stick” blood spot to be collected and shipped directly to the laboratory in a pre-paid envelope. All necessary components for the “finger stick” are included in a kit with a complete set of instructions for easy collection. For most of these tests, individual foods tested are organized within eight categories: dairy, fish, meats, shellfish, grains, nuts, fruits, and vegetables. With the results in hand, you can methodically and definitively eliminate the foods that are causing the symptoms from your diet. This means you can start feeling better fast.

How to Use the Results to Start Feeling Better

When you receive your results, all foods tested will fall into one of three immune reaction categories: high, moderate, and mild. The reaction categories are colored-coded for easy interpretation. Red is high, yellow is moderate, and green is mild. The simple approach is to eliminate the foods that fall within the red category. Those are foods with high levels of IgG and are probably increasing inflammation and countering your weight loss efforts. By the way, before eliminating any food, you might want to take a blood test that measures C-reactive protein. After a couple of months, repeat the test and see if your CRP level dropped. If it did, that’s a clear-cut sign that food sensitivities were causing your problems.

What You Need to Know

It seems that food allergies and sensitivities are on the rise. According the Centers for Disease Control and Prevention, three million children and up to ten million adults suffer from a food allergy or food sensitivity.2 So this raises a couple of questions. Are food sensitivities an additional risk factor for obesity and metabolic disorders? And are food sensitivities associated with chronic inflammation placing more of us at risk for age-related ailments, like heart disease and neurologic disorders? Well, since food sensitivity testing is easy and accessible, maybe it’s time to start testing and eliminating foods that trigger high IgG responses. This could be a big step forward in helping people lose weight and finally get rid of other mysterious symptoms.


  1. Exp Clin Endocrinol Diabetes. 2008 Apr;116(4):241-5.

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