When You Lose Weight, Here’s How Your Body Fights To Regain It For You

It’s well-known that intentional weight loss is often regained quickly, but it’s not always clear why.

Sometimes it is clear! For example, we wrote previously about how a person who has been on GLP-1 RAs may afterwards be even more inclined to put on fat than before:

❝Of the four studies that actually looked at the macros (unlike most studies), they found that on average, protein intake decreased by 17.1%. Which is a big deal!

It’s an especially big deal, because while protein’s obviously important for everyone, it’s especially important for anyone trying to lose weight, because muscle mass is a major factor in metabolic base rate—which in turn is much important for fat loss/maintenance than exercise, when it comes to how many calories we burn by simply existing.

A reasonable hypothesis, therefore, is that one of the numerous reasons people who quit GLP-1 agonists immediately put fat back on, is because they probably lost muscle mass in amongst their weight loss, meaning that their metabolic base rate will have decreased, meaning that they end up more disposed to put on fat than before.

And, that’s just a hypothesis and it’s a hypothesis based on very few studies, so it’s not something to necessarily take as any kind of definitive proof of anything, but it is to say—as the researchers of this review do loudly say—more research needs to be done into this, because this has been a major gap in research so far!❞

Read in full: Semaglutide’s Surprisingly Unexamined Effects

But that’s about GLP-1 receptor agonist drugs; what about dietary weight loss?

It can be quite different in terms of its mechanism, for example: The 3 Phases Of Fat Loss (& How To Do It Right!)

But new science sheds a light on where these things meet:

Of mice and menus

Researchers (Dr. Frankie Heyward et al.) did a mouse study showing that after weight loss, the body often continues generating persistent hunger signals for weeks, increasing the drive to regain lost weight.

The way that this happened suggests that the body is likely to biologically defend a previously higher weight, creating sustained pressure to return to that elevated weight rather than comfortably maintaining the lower one.

Notably, only mice whose food intake remained permanently restricted to match lean controls maintained their weight loss, suggesting that reaching a lower weight didn’t erase the physiological drive to regain. This suggests that the draconian methods discussed in our article “What Are The “Bright Lines” Of Bright Line Eating?” may work, at least for long-term weight loss, if not necessarily for happiness*.

^{*For health and happiness, we would suggest almost the opposite, per: Intuitive Eating Might Not Be What You Think and What Flexible Dieting Really Means 😎}

Back to the recent study: mice who gained weight the most quickly during their first four weeks on a high-fat diet were more likely to regain more weight later, which means early weight-gain responsiveness appears to predict long-term vulnerability.

Because both mice and humans share the same relevant pathways in this case, this has implications for GLP-1 receptor agonist use too, because while GLP-1 RAs can effectively reduce body weight, these findings suggest that underlying hunger biology will still persist and contribute to regain when treatment or calorie restriction stops.

You can read the new paper itself, here: Evidence of persistent hunger following dietary weight loss in mice

Want to learn more?

You might like these main features on getting your body just the way you want it, sustainably and healthily:

1. How To Lose Weight (Healthily!)
2. How To Build Muscle (Healthily!)
3. How To Gain Weight (Healthily!) ← this one’s specifically about gaining healthy levels of fat, for any who want/need that

And also:

Can We Do Fat Redistribution? ← yes we can, but there are caveats

Take care!