A Calorie is Not a Calorie | There are huge differences in the way different types of calories impact our bodies

This is from Mark's Daily Apple:

... Whole foods take more energy to process and digest than processed foods. In one example, subjects either ate a “whole food” sandwich (multigrain bread with cheddar cheese) or a “processed food” sandwich (white bread with cheese product). Both meals were isocaloric (same number of calories) and featured roughly identical macronutrient (protein, fat, carb) ratios. Those eating the multigrain sandwiches expended 137 calories postprandially (after their meal). The white bread group expended only 73 calories, a 50% reduction in the thermic effect of food.  Protein takes more energy to process and digest than other macronutrients. Compared to a low-fat, high-carb diet, a high-protein diet increased postprandial energy expenditure by 100% in healthy young women. And in both obese and lean adults, eating a high-protein meal was far more energetically costly (by almost 3-fold) than eating a high-fat meal. ...

[100 calories of sugar will make you fatter than 100 calories of fat.]  Study: ... For two weeks, participants either supplemented their diets with isocaloric amounts of candy (mostly sugar) or roasted peanuts (mostly fat and protein). This was added to their regular diet. After two weeks, researchers found that body weight, waist circumference, LDL, and ApoB (a rough measure of LDL particle number) were highest in the candy group, indicating increased fat mass and worsening metabolic health. In the peanut group, basal metabolic rate shot up and neither body weight nor waist size saw any significant increases. ...

[Calories counts are rarely accurate.]  Most foods at the grocery store have labels. Even restaurants are beginning to emblazon menus with calorie counts for each item. As humans, we implicitly trust the printed word. It looks so official and authoritative, and it spells out with great specificity exactly how many calories we’re about to eat.

Except studies show that’s not the case. Whether it’s the nutritional information provided by restaurants, the calorie counts on supposedly “low-calorie” foods, or the nutritional labels on packaged foods, calorie counts are rarely accurate. Food manufacturers can even underreport calories by 20% and pass inspection by the FDA.