Do Food Intolerances Affect Your Weight Loss

by Suzanne Hiscock
Are you struggling to lose weight even though you eat fairly healthy and you get in a bit of exercise?  And not only are you struggling to lose but you often feel unwell:  you might feel bloated, gassy, your bowel movements aren’t quite “normal” -- or worse yet, you get diarrhea.  You might even feel tired, get a headache -- the list goes on and on.

The problem might be hidden food intolerances.  Food intolerances can affect weight loss in few different ways.

And they’re a lot more common than most people think.

Food Intolerance is Different from A Food Allergy

A food intolerance is different from a food allergy. We’re not talking about food allergies here, where you go into anaphylactic shock or get hives.  Those can be serious and life-threatening.  

My best friend is deathly allergic to sesame seeds and carries an EpiPen around.  In that situation, when you’re allergic to certain foods, you need to steer clear of any traces of foods you're allergic to because it can have dire consequences. That’s when you need a to see a doctor immediately.  

But a food intolerance is different from a food allergy.  It’s literally an intolerance, meaning you do not tolerate a specific food very well and it causes immediate or chronic symptoms anywhere in the body.  You might feel the symptoms almost immediately or anywhere up to 72 hours later.

What happens when you eat a particular food you can’t tolerate is, your body releases a certain antibody (IgG) right outside of the lining of your gut. Then, certain chemicals, called cytokines, race throughout the body, causing inflammation and a variety of other symptoms.
This is what makes food intolerances so tricky to identify.  It’s not like you immediately eat the food and know right away what you ate made you feel terrible.  And the symptoms don't always manifest themselves in your gut where you would assume you'd feel it the most.

What are Symptoms of Food Intolerances?

You may even be surprised by some of the symptoms you feel with a food intolerance.  It’s not just digestive issues, like irritable bowel syndrome, gas, bloating and diarrhea.  It can affect your hormones and metabolism -- which, in turn, affect how your body loses weight.  It puts strain and stress on your whole body, which affects cortisol levels. High cortisol levels affect your weight loss by storing fat instead of releasing it, and by setting off carb cravings.

See:  How to Lower Your Cortisol Levels Naturally to Help you Lose Weight

Other symptoms you may feel include:
  • Inability to concentrate or feeling like your brain is "foggy"
  • Sweating, or increased heart rate or blood pressure
  • Headaches or migraines
  • Chronic muscle or joint pain
  • Sinus congestion
  • Fatigue or exhaustion after a good night’s sleep.
  • Anxiety or depression
  • Heart palpitations
  • Joint pains
  • Rashes or eczema

Let me ask you this:  what happens when most of us are feeling a little off, or tired?

We reach for comfort food.

We don’t exercise.

We don’t make healthy decisions. 

And that can push you further and further away from your weight loss goals. You get stuck into a vicious cycle, especially if you keep eating foods you are intolerant to.

How to Prevent Food Intolerances

What you need to do is to figure out which foods or drinks you may be reacting to and stop eating them.  If you don’t eat those foods, your body doesn’t react by releasing those chemicals and you don’t feel the symptoms.

Sounds simple enough, right?  Yet it can be SO HARD.

The best way to identify your food/drink triggers is to eliminate them for three full weeks and monitor your symptoms.  (I have a worksheet you can download to keep track. I’ll link to it down below.)

If things get better, then you need to decide whether it's worth it to stop ingesting these foods, or if you want to slowly introduce them back one at a time while still looking out to see if/when symptoms return.

Where to Start: Two Common Food Intolerances

Here are two of the most common triggers of food intolerances:  
  • Lactose -  found in dairy.  Eliminate dairy all together or look for a "lactose-free" label. Try nut or coconut milk instead (they’re not dairy at all).  (There's a recipe for nut milk down below.) You can also take lactase pills which are simply the enzyme needed to digest lactose.
  • Gluten - found in wheat, rye, and other common grains.  Look for a "gluten-free" label and try gluten-free grains like rice, quinoa & gluten-free oats.

This is by no means a complete list, but it's a good place to start because lactose intolerance is thought to affect up to 75% of people, while "non-celiac gluten sensitivity" can affect up to 13% of people. 

So, if you can eliminate all traces of lactose and gluten for three weeks, it can help confirm whether either or both of these, are a source of your symptoms.  (You can also try just one at a time. Pick either lactose or gluten. If you’re not sure which to pick, choose lactose because it’s the most common one.)
Wait, I hear you saying, aren’t dairy and grains part of the "food guidelines"? They are, but you can still get all of the nutrients you need if you focus on replacing them with nutrient-dense foods.  Nutrient-dense foods means foods that are high in vitamins and minerals, and fiber.
A reliable way to monitor how you feel after eating certain foods is to track it. After every meal or snack, write down the foods you ate, and any symptoms so you can more easily spot trends.
Click here to download a free copy of my How Food Feels Journal to help you track what you eat and how it makes you feel.

What you need to remember is symptoms may not start right away following a meal. You might find, for example, that you wake up with a headache the morning after eating bananas.  (Yes, some people are intolerant of -- and even allergic to -- bananas.  I find that so fascinating!)
You might be surprised what links you can find if you track your food and symptoms well.

IMPORTANT NOTE: When you eliminate something, you need to make sure it's not hiding in other foods, or the whole point of eliminating it for a few weeks is lost. Restaurant food, packaged foods, and sauces or dressings are notorious for adding ingredients that you'd never think are there.

You know sugar hides in almost everything, but did you also know that wheat is often added to processed meats and soy sauce, and lactose can even be found in some medications or supplements? 

When in doubt you HAVE to ask the server in a restaurant about hidden ingredients, read labels, and consider cooking from scratch.      

What If Eliminating Lactose and Gluten Doesn’t Work?

If eliminating these two common food intolerances doesn’t work, then you could go one step further to eliminate all dairy (even lactose-free) and all grains (even gluten-free) for three weeks.

Or your problem could be something else entirely. Go through your worksheets and see if you can spot any other trends.

At this point, I would strongly suggest you may need to see a qualified healthcare practitioner for help. Talk to your doctor or a registered dietician/nutritionist and bring along the sheets you used to monitor your symptoms. This will show them what you’ve tried to do and can help them pinpoint what to do next.


Once you figure out the foods you’re intolerant to, then it’s a matter of avoiding those foods as much as you can.  Make sure you look for hidden ingredients, too.

If certains foods were the problem, your symptoms should start to clear up and you’ll start feeling better.  Once you feel better, you won’t be reaching for food for comfort, you’ll sleep better and exercise a bit more, there will be less stress on your body -- and this will help you reach your weight loss goals.

As a nutrition coach,  I can help guide you towards healthy eating habits so you feel better, have more energy and reach your weight loss goals. Click here to check out my online program.

Recipe (dairy-free milk): Homemade Nut/Seed Milk

 Makes 3 cups
  • ½ cup raw nuts/seeds (almonds, walnuts, pecans, pumpkin seeds, or sesame seeds)
  • 2 cups water
  • ¼ teaspoon vanilla extract (optional)


Soak nuts/seeds for about 8 hours (optional, but recommended).

Dump soaking water & rinse nuts/seeds.

Add soaked nuts/seeds and 2 cups water to a high-speed blender and blend on high for about one minute until very smooth.

Strain through a small mesh sieve with 2 layers of cheesecloth. Squeeze if necessary.

Serve & enjoy!

Tip: You can double the recipe and store the milk in an airtight container in the fridge for up to 7 days.


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About the Author

Suzanne Hiscock is a PN L2 Certified Master Coach, ACE-certified Health Coach, as well as an ACE-certified Fitness Nutrition Specialist. For over 20 years, she's been helping people lose weight and get fit through her website,

And she’s really TRULY SORRY ABOUT THAT. You see, she didn’t realize she was contributing to diet culture; she just wanted to help people feel better. But losing weight isn’t the way to do it. She’s on a mission to change all that with an anti-diet approach. So, pardon the dust on the floor as the website gets revamped.