A new nutrition study says you could be racking up calories as soon as you turn on the stove. See which high fat foods actually get more caloric when cooked
It's well established that cooking carb- and protein-based foods increases their digestible calories. After all, imagine eating a raw potato or a raw piece of meat—since your body can't readily digest those foods uncooked, you won't get the bulk of the calories in them. Only when they're cooked can your body utilize those calories.
But is the same true when it comes to fats? Until recently, no studies had truly examined if cooked, fat-based foods were higher in calories than their uncooked counterparts.
A 2015 study published in the American Journal of Physical Anthropology did examine the topic. Researchers looked at the impact of cooking peanuts compared to blending them (like for peanut butter or in a smoothie). During the study, mice were fed raw or cooked peanuts. The results: The mice gained significantly more weight when they ate the cooked peanuts. Sure, the study was only done in mice, but scientists also looked at the structure of the different peanut diets, finding that cooked whole peanuts were substantially larger than raw whole peanuts. How come? Heating caused the peanut to swell and rupture, making the fat inside the cell walls available for digestion. Apparently, digestive enzymes can't get to those fats when the cell wall is intact. (See more of The Biggest Cooking Calorie Bombs Causing Weight Gain.)
Peanuts aren't the only nut (okay, technically legume) that have fewer calories than previously thought when uncooked, either. A 2012 study in The American Journal of Clinical Nutrition found that raw almonds have 20 percent fewer calories than originally thought. Again, this is because some fat remains intact within the cell walls of the nut.
There are plenty of other high-fat foods that you can eat raw or cooked: salmon, seeds, avocado (if you use it for baking, it's cooked), olives, and coconuts are just a few. You can also find raw nuts now easily at the market, and while nuts are usually cooked before blending for nut butter, that's not always the case. (Calories would be slightly higher if the nuts were roasted before being blended.)
But it's a bit dramatic to say you'll only eat uncooked nuts or fats in order to skimp on calories. (Cooked nuts are mighty tasty, and portions for both cooked and uncooked variations are filled with good-for-you nutrients!) While some calorie counts can vary greatly between raw and cooked, it depends on the food. And in the overall "big diet picture," when portions are kept in check, raw or cooked fats can be part of a healthy diet.
In fact, if anything, these studies show us that some of the science (like that for analyzing ingredients) needs to catch up with today’s foods as we eat them. For example, for over 100 years, we've been using the Atwater Factors to calculate calories in foods—a method that doesn't take into account the specific amount of calories increased in nuts (and other fats) when cooked. It'd be helpful to have a better calorie count on food labels so we can more accurately determine the amount of calories we're consuming.