You hear it all the time.
“I just started this new diet and lost 10 pounds of fat this week!”
“This new cleanse can help you lose 20 pounds of fat in 2 weeks!”
It’s tempting to believe these statements but there’s one major problem: they’re wrong. Let me explain.
Most people tend to confuse fat loss with weight loss. When you lose weight you may be losing weight in multiple areas, not just the fat department. Most of the weight lost during a rapid change is going to be water and carbohydrate, along with some muscle loss depending on how severe the diet was. In fact, you can easily replicate these magical “10 pounds in a week” diets by simply cutting carbohydrates out of your diet completely for 7 days.
Your body stores carbohydrates in the form of glycogen to provide energy, so by cutting carbs out of your diet your body will use up whatever you had stored, without refilling those stores because no carbs are available from the diet. Additionally, glycogen (the stored carbohydrates) carries a very large amount of water with it, so when you have a lot of carbs in your diet you’re going to store a lot of glycogen AND water. When you take those carbs out of your diet, you can lose massive amounts of weight very quickly simply because you are not refilling those glycogen stores and therefore lose a ton of water weight and carbohydrate weight. So if all you want to do is make the number on the scale move, cut carbs out of your diet and the number will move very quickly. The problem is you may not actually lose any fat, which is the more important issue.
Unless you plan on never eating carbohydrates again (which might make you a masochist, but I won’t judge) then the weight loss from depleting glycogen stores and water weight doesn’t actually mean anything. One of the most glaring issues is that you can only cut glycogen and water to a certain extent, after which you can’t lose any more. This is why low-carb diets and ketogenic diets are notorious for massive weight loss in the first week or two before the rate of weight loss slows down to a fraction of what it was. Once you’ve completely dropped the 10-20 pounds of water and carbs that you may have stored, you can no longer lose weight from glycogen/water depletion. Even more important though is the fact that this weight loss is not permanent. As I already mentioned, the only way to keep the weight from glycogen/water off of your body is to never bring carbs back into your diet. If you ever bring carbs back into your diet after you cut them out, you’re just going to regain the glycogen and water that you lost. This is one of the most common complaints about low-carb and ketogenic diets–people lose 15 pounds in 4 weeks after which they start eating carbs again and promptly regain 11 pounds. What happens here is that you wind up with only 4 pounds of actual fat loss (assuming you lost zero muscle), which is pretty standard for almost any diet.
Further adding to the glycogen/water weight problem is the fact that this weight changes almost every day, possibly multiple times per day. If you had 6 pieces of cake at the monthly “we just made up a reason to celebrate!” office get-together, then you just ate a lot of carbs which may reflect a little unusually on the scale. Even if you didn’t actually gain any fat, the scale may increase by 3 pounds just from increased glycogen and water weight resulting from yesterday’s carbs. Or if you happen to eat a little less chips one day than you normally do, your scale weight may drop 2 pounds in a single day even though you might not have lost a single ounce of fat. Basically, the scale will lie to you because its hard for you to differentiate between weight loss and fat loss.
So the next time you see a new book, cleanse, or advertisement say that you can lose tons of fat in a week or two, remember this article. A sucker is born every minute, try not to become one yourself.
In the next article, you can read why losing pure fat seems to be so damn difficult.
Lance understands both the science and art of nutrition coaching, which he combines with an extensive background in training the general population in order to teach individuals how to achieve their own transformation. When he's not busy obsessing over dogs, you can find him buried under a pile of exercise and nutrition research articles.