How Often Should You Eat? Part 2: Fat Loss

Because of the complex nature of this topic, I’ve broken it down into 5 parts: the first installment is meant to raise your suspicions about traditional advice; here we’ll focus on fat loss, and later posts are on muscle mass and health & longevity. The final installment will discuss how to create a metabolism capable of “Infrequent Eating.”

Ever notice the paradox in fat-loss advice? On one hand, you’re supposed to eat less—but on the other, you’re supposed to eat often to “keep your metabolism up.” I’ve dispelled the call to eat less in other posts (read the free preview of my Fat Loss eBook for a thorough understanding of this point), but what about the second point—does eating frequently favor weight loss?

This question needs to be approached from a few different angles:
Does eating frequently accelerate your metabolism?
Does eating infrequently slow your metabolism?
How does a “fast” or “slow” metabolism affect fat loss?

Does Eating Frequently Accelerate Your Metabolism?

The term “metabolism” refers to any and all chemical reactions taking place within your body; to refer to a slow or fast metabolism, then, is not very meaningful. However, these latter terms are generally meant to refer to the rate at which your body expends fuel (be it carbohydrate, fat, or protein), with the assumption being that a ”fast metabolism” will favor a leaner body by 1) preventing fuel from being stored within fat cells, and 2) burning fuel that has been stored as body fat—conversely, that a “slow metabolism” will favor increased body fat for the opposite of these reasons.

In Part 1 of this series, I answer this question of this section more thoroughly; the long and short of it, though, is: yes, eating temporarily increases metabolism. This is called the “thermic effect of food” because it is most easily measured as a slight increase in body heat after eating. This bump in energy expenditure is necessary for your body to digest that food and assimilate the nutrients therein.

But hold on—that doesn’t necessarily mean it affects weight loss. We’ll look at that after the next section.

Does Eating Infrequently Slow Your Metabolism?

First, we need to clarify how infrequent we’re talking about here. If you’re not going to eat anything for a week, then yes, your metabolism will slow down. But if we’re talking about the Infrequent Eating (IE) as described in Part 1 (where you would eat once at the end of the day), then no, your metabolism will not be impeded in any way to hinder weight loss.

Your metabolic rate is largely governed by various hormones, including: adrenaline, cortisol, estrogen, growth hormone, leptin, testosterone, thyroid hormone, and others—we’ll see these hormones again, so remember them. Indeed, the release of these hormones is affected by food intake, but you won’t see a significant drop in their levels as a result of IE. Furthermore, even with FE, these hormone levels will drop if you chronically eat less—in other words, eating less will cause your metabolism to slow down regardless of eating frequency!

Now for the most pressing question.

How Does Metabolic Rate Affect Fat Loss?

So we’ve seen that eating frequency does (kinda) affect energy expenditure. But does that mean it’s relevant to weight loss? Since we know we can eat rather infrequently without a hindrance to weight loss, we must assume that, in order to cause weight loss, the thermic effect of food is necessarily fueled by body fat...right? And if not, then FE doesn’t facilitate weight loss. To find the answer, we need to explore how fat cells are regulated. I tackle this topic in depth in Fat-Cell Physiology, but briefly:

There is no law of physiology which states either “excess” fuel must be deposited in fat cells, or “energy deficit” is necessarily compensated by depleting fat cells. Rather, it is the physiology of fat cells which determines if you get fatter or leaner.

Fat cells are enlarged by the actions of an enzyme called “LPL” and decreased by another set of enzymes called “FCL”; the size of any particular fat cell can be understood as the combined total actions of these opposing enzymes. Their level of activity is independently regulated by, both, triglyceride and various hormones.

Regarding regulation by triglyceride (a storage & transport form of fat), high levels outside of the fat cell (in the blood) activate LPL, and thus stimulate enlargement through uptake of fat. Conversely, high levels of triglyceride within a fat cell activate FCL and inhibit LPL, thus promoting reduction in the size of that fat cell. In this way, the size of a fat cell is regulated.

However, hormonal regulation dominates the regulation of fat cells. In general, a hormone called “insulin” promotes the storage of fat by increasing the activity of LPL and decreasing FCL. Conversely, several hormones (which we’ll refer to collectively as “anti-insulin hormones”) favor the reduction of fat cells by inhibiting fat-cell LPL and activating FCL.

Here, a distinction must be made: a type of LPL is also expressed on non-fat cells, which is hormonally regulated oppositely that of fat-cell LPL. Non-fat-cell LPL is activated by the anti-insulin hormones and inhibited by insulin. Further, the ability of non-fat cells to burn that fat is enhanced by the anti-insulin hormones. However, 2 of the anti-insulin hormones later favor the actions of insulin.

Whereas insulin is generally released in response to eating, when fuel availability is presumably high, anti-insulin hormones are released when fuel availability is (at risk of) running low—such as periods of starvation or exercise. Realize how this system of regulation ensures a basal level of triglyceride availability while discouraging excessive accumulation within cells and circulation. It also provides non-fat cells with increased fuel during periods of increased metabolic demand, and refuels fat stores after depletion.

In other words, there’s no reason the thermic effect of food should be fueled by body fat; FE, then, does not necessarily promote fat loss. However, let me tell you what happens when you chronically eat less.

What Happens When You Eat Less

Remember those hormones which determine your metabolic rate—adrenaline, cortisol, estrogen, growth hormone, leptin, testosterone, thyroid hormone? We’ve actually mentioned these twice—though I wasn’t explicit about it until now. These same hormones are the “anti-insulin hormones” which regulate fat cells. Can you guess why semi-starvation causes your metabolism to slow? That’s right, a decrease in these hormones. This helps explain many of the symptoms that accompany “caloric restriction,” including feeling cold, lethargy, weight plateaus, and total fat regain.

What Happens When You Eat Frequently

Now remember the other big hormone of fat-cell regulation, insulin. Remember, insulin is released when you eat (especially carbohydrate) and generally favors enlargement of fat cells. Every time you eat, then, you are favoring fat gain, NOT fat reduction! Further, chronically eating less actually causes your body to become MORE sensitive to insulin…while your anti-insulin hormones are being suppressed! Lastly, because insulin clears your blood of fuel (pushing it into cells and locking it there), it mimics starvation! In short, FE facilitates the experiences/events associated with eating less (feeling cold, lethargy, plateaus, and regain).

Conclusion

We’ve seen that, rather than facilitating weight loss, FE actually hinders it, favors enlarged fat cells, and facilitates the experiences we associate with eating less. Conversely, IE is preferable for weight loss, and can be done without any of the undesirable side effects caused by eating less. In the final post, we’ll discuss how this is possible; next, though, we’ll discuss the effects of eating frequency on muscle mass.

Thanks for reading. Be well,
Nicklaus Millican