Just about anyone who has tried to lose weight for at least a month or two has sooner or later experienced a very frustrating phenomenon: the weight loss plateau. It is something that happens when you begin to lose weight on a diet but, for no apparent reason, the weight loss stops, seemingly forever.
This happens even though you continue to take in far fewer calories than you need to maintain whatever weight you’re stalled at. That gap between what you weigh now and what you should weigh based on your current caloric intake can be baffling and frustrating. When it goes on long enough, you’re likely to just throw in the towel, admit defeat, and go back to your old eating habits.
Understanding why this happens can help you to be more patient with the process and to have reason to be hopeful about a positive outcome. So let’s try to understand why your body does this and what it means for you in practical terms.
We’ll begin with the understanding that your body works in the ways that it does because there is some selection advantage to it. Ultimately, your body is concerned about only one thing: survival. More specifically (and later I’ll explain why this is an important clarification), its job is to ensure the survival of your genetic line through reproduction.
Historically, humans have lived through frequent periods of food scarcity and those who were able to survive those episodes passed on their genetic hardiness to later generations. The ability to survive longer without eating is accomplished mainly by storing body fat when food is abundant and using that as a strategic reserve of energy when it’s not.
This has been called the “thrifty gene hypothesis.” The original idea behind this theory is that now that food abundance is the norm, while our bodies are still adapted for the lifestyle of hunter-gatherers, we are predisposed to keep storing fat for a famine that never comes. On the surface, that makes a lot of sense.
The main problem with this explanation is that there are hunter-gatherer societies today that do not store extra body fat during periods of famine. If the same was true of humans prior to the development of agriculture, that would throw a major wrench into the theory. If, on the other hand, it was an adaptation to feast-famine cycles related to agricultural factors, it wouldn’t leave a lot of time for this genetic trait to take hold so widely. (A mere 12,000 years, tops.) So how does it work?
That’s where the point about reproduction is relevant. Body fat helps with more than survival; it also enhances fertility. British nutritionist Andrew Prentice pointed out that the combination of viability and fertility both being enhanced by storing body fat can significantly speed up the process of genetic selection favoring the thrifty gene.
So that’s likely how – and why – it still works for us. How does that relate to the weight loss plateau? Because if your body senses that you’re suddenly taking in significantly fewer calories, it will “assume” (it’s easier to explain this as if our bodies are thinking this all out logically) that there is some food scarcity or even a famine going on. It does not assume you’re going to starve yourself if you have food available, so it doesn’t get the idea of dieting.
To make sure you’ll survive through the supposed famine, your body will slow down your metabolic rate, or how quickly you burn off calories, to conserve energy. It does this by reducing its expenditure on less vital needs, such as skin, hair and nail regeneration, and your mental and physical energy. It’s the same way we conserve energy by driving less during an oil shortage or conserving water or electricity during peak consumption in the summer months. That’s why people who are malnourished have flaky skin, dull hair, and brittle nails. It can also explain why you might have a hard time concentrating when you’re on a restrictive diet. (Aside from the fact that you’re thinking about food all the time.) Your body is doing everything it can to preserve that stored body fat for as long as possible because it may come in handy pretty soon.
This is why after initially losing weight, and feeling really hopeful, you experience long plateaus where your weight remains steady despite your best dieting efforts. It’s enough to make you want to give up the fight since you feel you’re doing everything you can. Well, you are; it’s just that your body is doing everything it can do to protect you from starving. You want to say “Thanks, but stop trying to help!” Well, don’t complain; that’s how your genetic line survived to the 21st century. The main challenge is to be patient; the laws of physics say that it can’t hold out forever and will eventually have to dip into the strategic fat reserves.
There are ways to minimize it, though. The best strategy is to try reassuring your body that there is no food shortage by eating smaller meals and smaller portions while eating more frequently. This way you’re still getting the same (reduced) amount of calories, but your body will understand that food is plentiful since you can eat whenever you want to, and that the calorie deficit is simply due to your choice to eat less for some crazy reason, not because of your inability to find enough food.
At that point, your body resumes the response that you would expect when you cut down on your calories, and you will once again lose weight.