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Weight Management Series: How to Gain Weight on the Low FODMAP Diet

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 Weight Management Series

In this installment of our Weight Management and the Low FODMAP Diet Series, my intent is to provide nutrition recommendations to help one achieve a healthy* weight.

It is not uncommon to experience mild weight loss during the low FODMAP Elimination Phase due to smaller portions and food restrictions, which for some may be desired.

For those struggling to maintain a healthy weight or are experiencing unhealthy weight loss, this article below, How to Gain Weight on The Low FODMAP Diet, will be a helpful resource. If you are trying to achieve a healthier, lower weight please refer to our article, How to Lose Weight on the Low FODMAP Diet. 

It is encouraged to wait until completion of the low FODMAP Eliminate and Challenge Phase before pursuing weight reduction for reasons stated in that article.

*A ‘healthy’ weight is determined by you and your professional health team – not by society.
How to gain weight on the low FODMAP Diet

How to Gain Weight on The Low FODMAP Diet

It is not uncommon to experience mild weight loss on the Elimination phase of the low FODMAP diet due to multiple food restrictions and reduced portions sizes to keep FODMAPs within a safe range.

This can be an issue for those who are under weight to begin with and/or are looking to gain weight or maintain their present weight.

Choose Your Low FODMAP Foods Wisely

While there are many low FODMAP foods available it can be overwhelming navigating this new eating pattern, which can result in a calorie deficit and subsequent weight loss. It is important to find suitable low FODMAP foods to replace your high FODMAP foods to maintain energy balance.

Please check out the many low FODMAP resources and recipes available here at FODMAP Everyday® including the Low FODMAP Shopping Lists to find low FODMAP alternatives to your typical high FODMAP food staples.

You can also easily build all of the low FODMAP meal plans you need with our Low FODMAP Meal Planner!

Work with a Registered Dietitian

We encourage you to work with a FODMAP trained RDN when completing the low FODMAP Elimination and Challenge Phase, as in some situations a strict Elimination Phase may not be the best approach.

For those who are already underweight, as defined by a BMI less than 18.5 (defined as your weight in kilograms divided by the square of your height in meters (kg/m 2), or those with multiple health issues, a FODMAP trained RDN can provide a safe, more personalized approach to help reduce IBS symptoms without being overly restrictive.

Our Best Tips for Healthy Weight Gain On The Low FODMAP Diet

Here are my tips to help one achieve healthy weight gain while following any phase of the low FODMAP Diet.

Consume Small, More Frequent Meals

Smaller, more frequent meals can help alleviate IBS symptoms, while large portions often exacerbate IBS symptoms. Aim for three meals and three snacks each day. A good rule of thumb is to eat every two to three hours.

Be prepared with low FODMAP, high calorie snacks when away from the home. An evening snack is encouraged; however use caution if this exacerbates reflux symptoms.

Higher Calorie Snack Suggestions:
Check out all the low FODMAP snacks on our Low FODMAP Shop

Make Every Bite Count

Add a little extra butter or oil when cooking your meals. Incorporate small portions of high fat foods to boost calories without adding too much volume. For example, top low FODMAP crackers with aged cheese or a low FODMAP nut butter or spread mayo (without garlic or onion) on both sides of your low FODMAP sandwich and use ⅛ Hass avocado (20 g) and cheese as fillings to provide extra calories.

Some low FODMAP crackers:

A focus on plant based fats such as avocado, nuts, and seeds is encouraged since these provide heart healthy monounsaturated fats. On average oils, nut butter, butter, and mayonnaise provide about 100 calories per tablespoon.

Low FODMAP High Fat Foods

Make Your Beverages Count

Sip on higher calories beverages to boost your calorie intake. Liquids often leave the stomach quicker than solids foods, which may help sneak in extra calories without negatively affecting appetite for the next meal or snack.

Low FODMAP Beverages
  • Lactose Free Whole Milk
  • Lactose Free Whole Milk Kefir – Green Valley Organics Lactose Free Kefir Plain
  • Lifeway Kefir – Plain, Natural Unsweetened, Strawberry, Blueberry, and Raspberry (these are 99% lactose free)
  • Orange, Cranberry, and Tomato Juice in safe portions
  • Low FODMAP teas and coffees with lactose free half-and half or lactose free whole milk sweetened with sugar or maple syrup.

Choose High Protein Foods

Protein is the building block of muscle and is an important nutrient in healthy weight gain. Consuming adequate protein can help minimize lean muscle mass which often occurs with involuntary weight loss. Proteins are naturally low FODMAP and recommended at every meal.

Protein is the building block of muscle and is an important nutrient in healthy weight gain. Consuming adequate protein can help minimize lean muscle mass which often occurs with involuntary weight loss. Proteins are naturally low FODMAP and recommended at every meal.

High protein low FODMAP foods include: chicken, fish, shellfish, beef, pork, eggs, cheese, firm tofu, tempeh, safe portions of canned and drained chickpeas and lentils, lactose free kefir, cottage cheese, and lactose free milk and protein rich milk alternatives.

Be sure to explore all of our recipes! Using the filter or search bar to find your favorite protein!

A few US-based higher protein plant-based milks include: Ripple Nutritious Pea Milk, 8th Continent Soy Milk (Original), Orgain Organic Protein Almond Milk (Unsweetened Vanilla and Lightly Sweetened Vanilla).

You may want to read: All About Low FODMAP Meal Replacements and Protein Shakes

Consider Nutrition Supplements

There are several nutrition supplements available that can easily be incorporated into easy snack options or fortified to make a higher calorie meal. Nutrition supplements often contain carbohydrates, fat, a hefty dose of protein, and several micronutrients to help fill in nutritional gaps.

There are several certified low FODMAP meal replacements and protein shakes to choose from, check out this article to learn more.

Ensure Plus Nutrition Shake, Ensure Regular Nutrition Shake, Ensure High Protein Nutrition Shake, Ensure Clear Nutrition Drink, BOOST High Protein Complete Nutrition Drink, and BOOST Optimum Advanced Nutrition Drink are likely low FODMAP since they are contain less than 0.5 grams or less of lactose which is suitable for those with lactose intolerance and contain no prebiotic fibers or fructose which are present in some of their other products.

Soy protein isolate has not been tested by Monash however it is likely low FODMAP since this is a protein that is isolated from soybeans.

Boost calories in your meal replacement and protein shakes by adding safe serving of a low FODMAP fruit (fresh or frozen), 1 to 2 tablespoons peanut butter, flax seed oil, flax seeds, chia seeds, or ⅛ Hass avocado (20 g).

Protein powders can also be added to cooked oatmeal, lactose free yogurt, lactose free whole milk or other low FODMAP milk alternatives.

Read more about protein shakes.

Sweeten Foods and Drinks with a Low FODMAP Sugar Source

Sure, consumption of large amounts of sugar is not very healthy however the WHO (World Health Organization) recommends an upper limit of 25 grams or 6 teaspoons of added sugar for women and 37 grams or 9 teaspoons of added sugar for men.

Low FODMAP sweeteners such as sugar (white, brown, and coconut at 1 teaspoon), maple syrup, ½ teaspoon clover honey, rice malt sugar, jams and jellies (made with sugar and low FODMAP fruits) provide about 50 calories per tablespoon and can easily be added to many foods and drinks.

Tips to Sweeten Your Day
  • Snack on 1 ounce/30 grams of dark chocolate or .5 ounce/15 grams of milk chocolate
  • Add maple syrup to lactose free yogurt
  • Sweeten coffee and tea with sugar
  • Add a safe jam or jelly to your low FODMAP bread and peanut butter
  • Enjoy one of our yummy low FODMAP desserts

The low FODMAP diet just might be your path to better health and we hope to be part of your journey!

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