Low-Carb? Low-Fat? Does it matter?
Conflict regarding nutrition advice is rampant. This is due to multiple reasons and influences (think about those Netflix documentaries), but one of the biggest reasons for conflict and misunderstanding is the nuance of the subject. How your body metabolizes food and stores it as fat is complicated when you get into the nitty-gritty, causing the spread of misinformation because people only understand a part of the whole picture.
“A little learning is a dangerous thing… there shallow draughts intoxicate the brain, and drinking largely sobers us again.”
-Alexander Pope, An Essay on Criticism
The article below is mostly written for all the people who ask me “Does make you fat?” If you don’t care too much about the details, here’s the summary:
To lose fat, the most important thing is to eat fewer calories than you expend. Different diets (keto, vegan, paleo, eating “clean”, etc.) can be useful, but not because they inherently burn more fat. They can make it easier for people to eat fewer calories, which in turn causes fat loss.
One simple and absolute truth needs to be clarified before we go any further: to lose fat, you must consume fewer calories than you expend. To gain fat, you must do the opposite. It may sound arrogant, but any alternative explanation (e.g. too many toxins into your fat cells) is wrong. If you want more clarity on that, feel free to reach out to me directly on Facebook. Also, we have to get our semantics straight here: Weight loss can mean losing weight in any form: most notably water, fat, muscle, and feces. Here, we’ll be discussing fat loss specifically.
In the simplest and most technical sense, a calorie is a calorie. However, in the context of fat loss, the sources we get our calories from matter mostly due to digestive efficiency and how easily a macronutrient carbs, protein, fat is converted to energy. How well certain macronutrients conserve muscle also matters, but moreso in the long term.
Fat, protein, and carbohydrates are absorbed at slightly different rates in the body. Fat has a slightly higher absorption rate than most proteins and carbs, but that probably won’t make a massive difference in most peoples’ diets. It should also be noted that fiber, while technically a carbohydrate, is either minimally absorbed or not at all (Fiber is awesome for fat loss, check it out).
After you eat and digest a certain macronutrient carbs, protein, fat , one of two things happen: it’s either used immediately or stored in some way. Being stored does NOT always mean it’s stored as fat. Fat is either stored within muscle or in fat cells (this does NOT mean dietary fat automatically makes you gain fat), carbohydrates are either stored in muscle or the liver if not put to use immediately as blood glucose, Contrary to common "knowledge", it’s very uncommon for carbs to be stored as fat. THEY CAN STILL CONTRIBUTE TO WEIGHT GAIN, just indirectly. and protein is stored as muscle tissue.
Here’s the thing- if you take two very different diets in terms of macronutrient composition (high-carb and low-fat vs. high-fat and low-carb), but you eat and absorb an equivalent amount of calories from both diets, how much weight you lose or gain will be the same with both diets, and fat loss will be similar (although carbohydrates help retain muscle better during weight loss). Carbs do not inherently make you fat, and neither does fat. I don’t think I’ve ever known someone to blame protein as a fat-gaining bogeyman
Here’s an overly simple Metabolism changes due to weight loss make the math a little more complicated in reality example to illustrate this whole thing: Let’s say you need to eat 2000 calories to maintain your weight. To lose about 1lb/week, you would need to eat 1500 calories/day. If, for the sake of simplicity, you ate a 1500 calorie 100% carbohydrate diet, you may burn a lot of carbs for energy, but it doesn’t matter because your body still needs to burn 2000 calories to keep you alive. You’ll still have an energy deficit of 500 calories, and your body will burn that by tapping into your fat stores. If you ate a diet of 100% fat, you’ll still need to make up that 500 calorie deficit by tapping into fat stores. Either way you slice it, you’ll burn 500 calories of body fat (and maybe a little muscle).
All that being said, the nutritional value of your food (vitamins, minerals, phytochemicals, etc) obviously matters for health. You can eat a diet entirely composed of junk food and lose weight, but I think most of us know we should be eating for health. This is beyond the scope of this article, but the nutritional quality of food does tie into weight management also, influencing cravings, gut health, and other factors.
Don’t dogmatically consider one nutrition strategy to be the best. Disregarding individual differences, you’ll lose the about the same amount of body fat whether you cut calories from carbs or fat. The right strategy is going to depend on your unique differences and what makes the fat loss process easier. That is where it gets more complicated.