Your Hunger Hormones, Your Appetite and Your Weight

Let’s talk about hunger…the feeling can range from “I'm a little hungry, but can wait to eat” to “I'm so hungry I want to eat everything in sight,” — for this, ghrelin is responsible.

Let’s talk about satiety (aka: the sense of being full)…the feeling can range from “I sense food in my stomach but I can continue eating” to “I'm Thanksgiving full with no hunger whatsoever” — for this, leptin is responsible. 

Leptin and ghrelin are two hormones I call the “hunger hormones.”

Leptin: Appetite Suppressor

Leptin is made by our fat cells and decreases our appetite, hence the reason I call it the appetite suppressor. Leptin is signaled when we have sufficient calories coming in, and in the big picture, it’s an important regulator of energy balance. Leptin also boosts our metabolism by encouraging the body to burn those calories we have eaten.

Under desirable circumstances, as the levels of leptin rise in our bloodstream, ghrelin levels fall and vice versa. This makes you feel full and satisfied after a meal.

In an obese individual, you may think leptin levels are low and ghrelin levels are high, and it turns out the opposite is actually true.

It's a vicious cycle that goes like this:

1. Eat more, gain body fat.
2. More body fat means more leptin in the fat cells, but the proper leptin signalling is disrupted.
3. The brain thinks you’re starving, which makes you want to eat more.
4. You gain more body fat and become hungrier.
5. You eat more and gain more fat.
6. And so on.

Obesity actually leads to increased leptin levels and decreased ghrelin levels. Many researchers think this is due to leptin-resistance, which most likely involves a time period of overeating, resulting in the leptin system becoming so messed up it leads to prolonged defects, similar to insulin resistance.

Ghrelin:The Snacking Hormone

When I hear the word ghrelin, I think of “gremlin,” and in my opinion, that’s a great way to describe this little hormone monster! Secreted primarily by the stomach, ghrelin increases our appetite and tells us, “Time to eat!” Levels fluctuate over the course of the day in relation to food intake—they rise before meals and fall rapidly after ingestion. This little monster can be blamed for those uncontrollable urges to snack and, like leptin, is also a key player in body weight changes over the long term, and unfortunately, not in a good way…

Weight loss significantly increases ghrelin levels, regardless of the weight loss method (ie: calorie restriction, illness, etc.). This seems to be the reason so many people have such a hard time not only losing weight, but also keeping it off.

The Microbiome and Its Influence On Appetite and Satiety

There's a very fascinating connection between a person's gut microbiome and their weight, appetite and satiety. It seems as if ghrelin and leptin are not the only two factors involved in body weight.

Recent research shows our gut microbes are directly participating in an appetite regulatory circuit by releasing bioactive molecules that tell us whether we are full or still hungry. It seems these bacteria may be undermining our self-control when it comes to eating and appetite and sending us unwanted signals.

So with these two strong hormones bidding against us, is there anything we can do to enhance the action of leptin and ghrelin?

Yes!

1. Don’t skip meals. Skipping meals leads to an increase in ghrelin levels, with a nearly twofold increase immediately before each meal. If that won’t cause you to overeat, I don’t know what will! This goes the same for under-eating of any kind.

After eating, ghrelin takes 1-2 hours to decrease, so if you find yourself continuing to snack after a meal, ghrelin is to blame.

2. Take fish oil or cod liver oil. Omega 3 fatty acids are linked to decreased hunger. I recommend taking 1 Tbsp oil, directly off the spoon, immediately upon waking up in the morning.

3. Eat enough protein. Even when someone is restricting their calorie intake, eating a higher proportion of protein foods can help control their appetite.

4. Include Fiber, specifically a type of fibre called psyllium fiber. This type results in a decrease in ghrelin.

5. Get Enough Sleep! Ghrelin has been shown to increase in our bodies with sleep disturbance. In fact one study shows even just ONE NIGHT of sleep deprivation can cause a rise in levels and an increased appetite. Leptin is also affected by sleep deprivation. No wonder there’s a connection between lack of sleep and obesity.

Bottom Line: It is very clear leptin, ghrelin, and your gut health play major roles in energy balance, but there are still many unknowns. As of now, Eat Real Food, Eat Regularly, Eat Balanced, and Sleep, and you’ll be on the right track.

In Health and Happiness,

Kelly Harrington, MS, RDN

Registered Dietitian Nutritionist for Healthy Goods

 

References:

1. MD Klok, S. Jakobsdottir, ML Drent. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obesity Reviews. 24 Aug. 2006. Vol. 8, Issue 1.  

2. SK Fried at al. Regulation of Leptin Production in Humans. J. Nutr. Dec. 1, 2000.130:12:3127S-3131S.