Are all calories created equal? I’m here to end the debate.
I’ve referenced this debate numerous times in previous blog posts, so I figured it was time to justify my feelings on the topic.
Herein lies the discrepancy, and also the fundamental reason that people can find a preponderance of evidence to support both sides of the argument: how strictly the caloric intake was controlled in the study. Let me specify further: was there adequate protein intake in the diet and were the subjects allowed to auto-regulate food intake or were their meals prescribed for them?
As you can imagine, when the two factors above are manipulated, the results of the study can vary wildly.
First off, as I’ve stressed time and time again, if protein intake is not kept at adequate levels (i.e., .8 g/lb. as a bare minimum), then the results of dieting efforts will be severely compromised. I’m ready and willing to concede that if you compare higher and lower protein intake diets, then the higher protein diet will almost always trump the lower — given that the calories are isocaloric, i.e., the same intake. In that case — the case of calories from protein vs. other macronutrients — a calorie is not a calorie. This is exactly why setting protein intake (after setting total caloric intake) is such a vital part of an effective fat-loss diet.
After establishing that protein calories are the most important calories and are relatively inflexible fixtures of effective diets, we can then examine what happens when the other macronutrients (carbohydrates and fats, and content thereof) are manipulated. The answer, (not) surprisingly, is very little. Assuming calories and protein are held steady, where the rest of the deficit comes from doesn’t really matter. Weight is lost at the same rate; furthermore, the composition of the weight lost remains the same. Kind of makes all the “brown rice and sweet potatoes or YOU’RE GONNA DIE!” people look silly, right? I wanted to point out that this occurs in situations where calories are very tightly controlled, i.e., people are not allowed to eat at will. Sure, fibrous carbs like brown rice may slow gastric emptying time, but research has also shown that the most satiating food is white potatoes. I don’t know about you, but I like feeling full while dieting. Again, this is not to say that sweet potatoes don’t work while dieting, but they certainly don’t make you lose weight any faster when calories are equal. Seems obvious, but you’d be surprised how angry asserting fact this makes people.
The other side of the coin is the studies where people are allowed to eat whatever they want given certain guidelines. What’s interesting about these studies is that we are actually able to derive why certain dietary strategies indeed work if we peel back the layers a bit.
For example, let’s examine what happens when someone is asked to reduce dietary fat to a certain level, but no other recommendations are given. Inevitably, that person loses weight because fat is the most calorically dense of all the macronutrients. For every gram of fat slashed from the diet, the person is giving away the accompanying roughly 9 calories that go with it. In long-term low dietary fat diets, however, most people end up gaining the weight back because that newly absent dietary fat has been replaced with a commensurate amount of carbohydrates, and excessive consumption of carbohydrates (especially simple carbs) has been linked to overeating.
Similarly, tell someone to reduce or remove carbohydrates from their diet and there is the initial weight-loss effect of removing a large portion of calories from the diet, as well as a marked reduction in water weight because the body holds less water on a low-carbohydrate diet. Most people eat less initially simply out of lack of options due to the removal of an entire food group (the most common food group in a typical American diet to boot; sometimes more than 50% of caloric intake). Another common mistake is confusing the quick loss of several pounds after embarking on such a diet for fat-loss. Quite simply, it’s not. It’s just water, as mentioned above.
I just wanted to note that individual variances in rate of weight-loss from diet to diet and differing levels of caloric intake are more than likely due to individual metabolic idiosyncrasies. Just because your best friend tried diet X and found it superior to all others doesn’t mean it is, per say. I’ll tell you one thing, though, more than likely diet X — if it worked for your friend — had adequate protein intake and caloric intake below maintenance.
So are all calories created equal? Is a calorie just a calorie? Strictly speaking, no, but for practical application I say YES! With a few caveats (c’mon, there’s always a catch):
1) Sufficient protein intake always trumps lack thereof. If you’re not eating enough protein and not meeting your physique goals, start here.
2) When tightly controlling caloric intake (along w/ #1, of course), the breakdown of the rest — carbs and fats — doesn’t really matter. Not enough to be statistically significant.
3) For folks seeking extremely low levels of body fat or the seriously obese, there may be exceptions to these rules, but these are outliers and shouldn’t concern the average dieter.
This post, coupled with my previous post, should give you all the information you need to set up an effective fat-loss diet. If you still need clarification on anything, just ask!