Several months ago, I wrote an article answering the question: Is saturated fat bad for you? One of the things it touched on to explain the discrepancies between studies regarding saturated fat’s role in heart disease was that we need to appreciate what foods are supplying the saturated fat.
Earlier this month, a study was published providing further evidence that the health effects of nutrients are influenced by the foods supplying them. Specifically, this study demonstrated that eating full-fat cheese had different effects on blood lipids than eating reduced fat cheese plus butter, both of which had different effects than eating the main constituents of cheese without the cheese food matrix being present: micellar casein protein, butterfat, and calcium.
The effects weren’t huge and probably meaningless from a pragmatic standpoint, but it served as a proof-of-principle study that our focus can’t be on just calories and macronutrients. Other studies comparing cream to butter oil and cheese to fatty meats have reported similar food-based discrepancies.
Paleo diet vs the ADA
One of the best examples, in my opinion, comes from a randomized controlled trial comparing the health effects of eating calorie- and macronutrient-matched diets based on foods promoted by either the Paleolithic diet or the American Diabetes Association (ADA) dietary recommendations.
All food was provided to the study participants, and the diets were both about 20% protein, 25% fat, and 55% carbohydrates. The Paleo diet excluded dairy, legumes, cereal grains, and potatoes — all of which were allowed in the ADA diet — and instead relied more heavily on starchy tubers, fruits, eggs, and nuts. Both diets included lean meats.
Despite the if-it-fits-your-macros mantra, the Paleo diet group saw better improvements in their glycemic control and blood lipids. It’s important to note that none of these differences were statistically significant between the two groups, but that is likely a result of the small sample size (n=24), short study duration (3 weeks), and medication use by the participants (19 on metformin and 11 on statins).
I believe that nuts serve as another great example of why food choice is important, albeit for a different reason. Nuts contain a plant cell wall that encloses the fat particles, rendering them unavailable for digestion and absorption. Thus, less chewing means more intact cell walls that interfere with the digestive process.
A handful of studies have demonstrated that walnuts provide about 21% less calories to be used by the body than they contain, almonds about 24% lower, and pistachios about 5% lower. Of course, individual values ranged from 0–64 % lower.
We have some observational data linking the use of high-heat cooking methods (broiling, barbecuing, or roasting) to an increased risk of type II diabetes.
There is also a year-long controlled trial suggesting that using gentler cooking methods (boil, poach, stew or steam) instead of high-heat cooking methods leads to substantial improvements in insulin sensitivity.
A separate controlled trial comparing calorie- and macronutrient-matched diets either high or low in advanced glycation endproducts (AGEs) found that the low-AGE diet resulted in greater insulin sensitivity and lower insulin secretion rates during a glucose tolerance test.
So, taking the same slab of meat and grilling it over an open flame could affect your health differently than if you stewed it. But that’s the same exact slab of meat.
Calories and macronutrients matter, but so do the foods we eat. We need to appreciate the role that the food matrix plays in health and disease. To ignore it is ignorance.