As an online coach, gym owner, and personal trainer, if there’s one thing I get asked more than “How do I lose body fat?”…I don’t know what it is. More than anything else, fat loss is the question.
How do I do it? How fast can I lose it? Should I go “paleo”? What about high fat? Is that good?
I’ve heard that putting butter in my coffee will cause me to drop fat so fast I’ll be almost unrecognizable overnight! However, by far the most asked question is…
“Are low carb diets the best way to lose fat?”
To answer that question, we need to look at a few things. Not the least of which is…
How Does Fat Loss Happen?
To answer the question of “are low carb diets the best way to lose fat”, we need to go straight to the source of the issue. Fat loss. How does it happen? What mechanisms must take place, what things must be in order, to cause someone to lose body fat? Thankfully, the science is pretty clear here.
In order to lose body fat you MUST be in a calorie deficit. Plain and simple. You absolutely must burn more calories than you consume in a given day, week, month, etc. There is absolutely no way around this fact. In other words, if it takes your body 2500 kcal/day to maintain your current weight you MUST consume less than that, over a predetermined period of measurement (day, week, etc.), to achieve any substantial weight loss. Now, there will be a natural ebb and flow to your weight due to water, stomach contents, etc. but the point remains the same.
To actually lose fat and/or weight, you must eat less than you burn.
Weight a minute…
See what I did there? Weight instead of wait… Get it? Okay, moving on..!
In order to truly discuss the issue of low carb diets and fat loss, we need to address something. There is an absolute difference between weight loss and fat loss: losing weight is one thing and losing body fat is another. Now, true, most of the time when weight loss occurs there will be some fat loss as well. However, weight loss can happen with significant muscle loss as an unwanted (and unnecessary) side effect if you’re not careful.
Many times, low carb proponents will cite “weight loss” as the ultimate success of their diet. You, on the other hand, as someone who is interested in muscle retention and FAT loss should be less concerned about scale weight. The ugly truth is the scale weight can lie, and if often does.
Remember how I said that water content can greatly affect weight loss, i.e. what the scale tells you…? Well, low carb diets are notorious for helping people drop water weight. Don’t get me wrong, water weight is still weight, but it is most certainly not body fat. This can make low carb diets look like the be all, end all, of body fat reduction. In fact, they may actually be detrimental to actual body fat loss.
Training Intensity, Muscle Retention, and Carbohydrates
Now, we’ve addressed why low carb diets can appear to help someone lose body fat faster when in reality, they just don’t. Thus far, however, we’ve not made a good argument that low carb diets can be detrimental to body fat loss, until now. I can hear you now, “I mean, if low carb diets can help me lose a bit of water weight faster, then why not? Water weight is still weight.”
That is totally true. I can’t make an argument there. I can (and will) make an argument for an instance that a low carb diet is inferior to a more moderate/high carb approach when it comes to actual body fat (as opposed to just weight) loss: gym performance. In order to build and maintain muscle mass, you need to be able to train intensely. You need to be able to progressively overload your muscles in some way. Progressively overloading can be adding weight to the bar, adding reps, doing more work in less time, etc.
To train intensely and progressively overload consistently, your body needs carbohydrates. Glycogen (the stored form of carbohydrate in your muscles) is far and away your body’s preferred fuel source for short duration, high intensity activity, such as lifting weights. In order to maintain muscle mass while in a caloric deficit (remember, this is required for body fat and weight loss of any sort) you must be able to continue giving your muscles a reason to exist.
For lack of a better word, you need to convince your muscles that they need to stay big and strong. We do this “convincing” by lifting weights and continuing to progressively overload our muscle. See where I’m going here?
If you’re attempting to progressively overload your body in the gym while limiting the fuel source for your muscles, you’re fighting a losing battle. Eventually, you’ll begin to regress and give your body less and less reason to maintain its current strength and size. Remember, we want to shift our body composition (the ratio of muscle/fat on your frame) to “less fat” and “more muscle”.
To do this most effectively, it makes sense to keep as MUCH muscle mass as possible while dropping purely body fat (or as close to it) as quickly as we can.
So Why Do SO Many People Lose Weight on a Low-Carb Diet?
This is a great question and one that is relatively simple to answer. Low carb diets, for some, make eating in a calorie deficit more manageable.
This happens for a few reasons:
When carbohydrates are reduced, many of the foods with the highest propensity to overeat are removed as well. High sugar, high carb breakfast cereals, ice cream, cakes, etc. are typically excluded when someone embarks on a low carb diet plan. By simply removing these foods, individuals take away a large portion of what they would typically eat (or overeat) on.
Low carb diets need something to make up for the lack of carbohydrate on a calorie level so protein is inevitably raised. When you remove a large portion of food from someone’s daily intake, they are going to make up for it somehow. Many people will unconsciously fill this calorie “hole” with protein. Protein is very satiating and, oftentimes, causes someone to “fill up” faster. As we mentioned earlier, protein also helps with muscle retention, which can allow for a better ratio of muscle/fat loss (favoring more fat loss and less muscle).
Similar to the above point, when carbs are reduced fat is often increased in the diet. Fat, like protein, is very satiating and will many times cause someone to eat less without even thinking about it.
So, sure, low carb dieting can work BUT to answer our question: “are low carb diets the best way to lose body fat?”
I think we’ve made a good argument that not only is low carb dieting not the best way to lose body fat but can actually be detrimental to those interested in performance and body composition.