The Science Behind Why It’s so Hard to Keep off Those Shed Pounds (Part 1)

We’ve all seen the headlines recently about one of our favorite TV shows – The Biggest Loser:

‘The Biggest Loser’ contestants gain again: Why weight keeps coming back

After ‘The Biggest Loser,’ Their Bodies Fought to Regain Weight

‘Biggest Loser’ Study Examines Why Contestants Gain Back the Weight

And if you follow our blog, you may have also read how Dan and I fell off the wagon Post-Shows:

A TOAST: To Water! The solution to all of life’s problems!

Post Show Rebound

It’s a grim statistic: Most people who lose weight will most likely put that weight back on (and maybe then some) within a year.

So.. naturally.. I’m assuming the question that’s on all of your minds must be “WHY?”

Well, there are many reasons, but for our intents and purposes, let’s just focus on the biological reasons today.


First and foremost, our bodies have a natural appetite and that appetite is regulated by hormonal mechanisms that try to maintain homeostasis (i.e. keep things in a stable equilibrium) over the long period of time. When we consistently take in less energy (i.e. food/calories) than we use through basal metabolism and activity (i.e. when we’re on a diet), our bodies respond by making us hungrier.

Our bodies don’t generally want to change. They like everything to stay the same. If we try to change things, our bodies will respond with compensation mechanisms, such as revving up our appetite hormones – leptin and ghrelin.

Leptin and ghrelin play a big role in regulating appetite, which consequently influence body weight/fat. While leptin decreases hunger, ghrelin increases hunger.


The amount of fat mass we have correlates to the amount of leptin we produce — the more fat, the more leptin. The leptin we’ve then produced tells the brain that we have enough fat, so we can then eat less or stop eating. Therefore, the more fat you have, the more leptin you make – the less food you’ll eat. And conversely, the less fat you have, the less leptin you make, and the hungrier you’ll be.

While, leptin is a result of a buildup of fat and consequently a long term regulator of body weight, ghrelin is more short term.

Your stomach makes ghrelin when it’s empty. Ghrelin is high before you eat and low after you eat. Ghrelin basically tell your brain, “Hey I’m hungry! When do we get to eat?”


When you lose a significant amount of weight, your body goes into “starvation mode.” Your system slows its production of leptin, a hormone that suppresses your appetite, while at the same time pumping up your levels of ghrelin, a hormone that makes you hungry.

And so the cycle begins…..


Tune in next week for Part 2 in which we’ll cover ways to try and keep your weight in check and try to fend off those unwanted/already shed pounds!

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