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  • Writer's pictureJustine Chriqui, McGill Dietetics Student

What is Food Combining and is there evidence behind it?

Have any of your clients asked you about food combining diets? Have you noticed them gaining popularity on social media? Food combining diets have been widely popular amongst health and fitness gurus for years, so let's delve into the evidence behind them.

What is Food Combining?

The principles of food combining suggest that pairing certain foods can either help or hinder one's health. Its rules suggest that combining certain foods incorrectly can cause unwanted health and digestive effects.

There are two beliefs that create the foundation of food combining diets. The first suggests that since foods are digested at different speeds, combining slow-digesting foods (like fats and proteins) with fast-digesting foods (like fruits and vegetables) will prevent "optimal digestion" and therefore cause health consequences.

The second belief is based on foods needing different enzymes to break them down; since the enzymes are activated and work at different pH levels in the gut, this belief implies that foods requiring different pH levels cannot be digested optimally at the same time.

Overall, if these rules (and others of each particular food combining diet) are not followed, it is believed that negative health outcomes will occur, such as disease, digestive distress, and the production of toxins.

Common Food Combining Rules

In general, foods are categorized as carbs/starches, fruits, vegetables, fats, and proteins. Some diets take it a step further and categorize foods as acidic, neutral or alkaline. Here are some of the most common Dos and Don'ts of food combining:


  • Always eat fruit on an empty stomach

  • Pair protein with non-starchy vegetables

  • Pair fats with non-starchy vegetables

  • Pair carbohydrates with non-starchy vegetables

  • Always wait 3-4 hours between meals before switching categories

  • Only consume dairy on an empty stomach


  • Mix starches and protein at the same meal

  • Mix fats and proteins at the same meals

  • Eat melons with other foods or fruits

  • Drink liquids with meals

  • Combine starches with acidic foods

  • Combine different types of protein

  • Eat fruits and vegetables at the same time

The History of Food Combining

The roots of food combining are from Ayurvedic practices in ancient India (see some guidelines here and here), though principles of food combining gained popularity elsewhere in the mid-1800s. In the early 1900s, the Hay diet revived its principles once again, and food combining became foundational to many more modern diets we know today.

Does it Work?

After searching through various scientific research engines, there is seemingly one article that includes food combining in its intervention. The study evaluated how low-calorie (1100 kcal) "food combining" vs balanced diets influenced weight loss in 54 participants with obesity. Participants were randomly assigned either diet, and they followed the diet plans for 6 weeks.

Upon completion of the study, the participants in both groups experienced weight loss, however, the degree of weight loss in kilograms was insignificant between the two. The duration of the intervention was quite short, so it is difficult to know whether more long-term differences may have occurred or whether there may have been improvements in digestion; however, with such a lack of evidence (and the intense restrictions of following a food combining diet), there's likely more cons for following such a diet than pros.

The Bottom Line

There is minimal evidence suggesting that food combining offers health and digestive benefits. There are certain food combinations that we know are beneficial (such as iron sources and vitamin C, fat and fat-soluble vitamins, calcium with oxalates, consuming a variety of plant-based proteins throughout the day); however, the principles of food combining were developed at a time where we did not have the extensive knowledge of health and digestion that we do today, so food combining diets are likely more fictitious than factual.

If your clients find that a food combining diet works for them, there may not be any harm in doing so; however for clients who are wanting a more positive relationship with food, it may be best to steer away from food combining and stick to the evidence-based nutrition guidelines we have today.

Thanks for reading!

-Justine Chriqui, McGill Dietetics Graduate Student


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