I’ve heard a lot about how combining different foods within meals can lead to more or less fat loss/muscle gain. Is there evidence to support this?

I’ve read a few (non-research) articles about the supposed benefit of combining or separating certain foods in order to optimize digestion.  Overall, I’m not buying it.

A term you may have heard or read about is ‘dissociated diet’.  The idea behind this is that you are supposed to eat one food group at a time.  The claim is that it will be easier for your body to adjust to and digest and therefore increase nutrient absorption.  This is commonly done on a weekly basis (Monday is grains, Tuesday is protein, etc) or daily (breakfast is grains, lunch is protein, etc.).

The first issue with this eating pattern that comes to mind is blood sugar levels.  If you have an entire meal/day of fruit, although the micronutrients are great, there is a ton of sugar.  The same could be said for grains.  If you eat a bunch of grains or fruit without any fat to slow the digestive process, you’re essentially dumping large amounts of glucose into your bloodstream.  This signals a strong insulin response which could contribute to insulin sensitivity issues as well as throwing your hunger and satiety signals awry.  Going without protein for extended periods is also not great for your muscles and organs.  And don’t forget that at least 60% of your brain consists of fat.

The limited research available on fat loss includes a study done on 54 obese patients in a hospital setting.  They compared a dissociated diet (25% protein, 47% carbohydrates, and 25% fat) against a balanced diet (25% protein, 42% carbohydrates, and 31% fat).  Both diets were of 1100 calories a day so weight loss was to be expected.  Both groups lost weight in similar amounts and the only difference mentioned in the research was blood pressure improvement with the balanced diet.

When it comes to digestion, our body has specific routes for each food group.  More accurate still, each macronutrient gets its own handling process.  For example, an avocado has fat, carbs, and protein.  To say that eating an avocado will somehow disrupt your body’s ability to efficiently digest a bowl of pasta isn’t true.  The tools your body uses to handle protein is not only different than the tools used to handle carbohydrates but it also happens in different locations of the digestive tract.  Carbohydrates (in both the avocado and pasta) start to be enzymatically broken down in the mouth, skip the stomach, and then get further broken down in the small intestine.  Protein (in the avocado and pasta (if whole grain)) is only broken down in the stomach and then absorbed in the small intestine.  When it comes to absorption, each has its own specific door.  Protein will go through the protein door while carbohydrates will go through the carbohydrate door.  There is no crowding or blocking of doors because they don’t share keys.

Until more research is available, I wouldn’t recommend this pattern of eating.


Tony Scartozzi

Author: Tony Scartozzi

Tony Scartozzi was born and raised in a small town in Eastern Washington. After moving to Seattle in 2001, he attended Bastyr University and graduated with a degree in Nutrition. Driven by his passion for public health, his career has spanned the nonprofit sector, senior housing resources, food service training, and now works for a nutraceutical company that produces market-leading plant extracts used for supplemental health. Observing the severe disparity between advertisement spin and research-based knowledge, Tony has spent many years trying to identify and reconcile the difference. With Tony’s parents’ age beginning to show, his desire to investigate health-related topics has become a very personal one.

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