How Dieting Hurts Your Hormones

We’ve said it a lot: diets don’t work. In case you haven’t heard, when people lose weight on fad diets, 95-98% of dieters regain the weight plus more. 

Beyond the scale, something people aren’t talking about is the effect of dieting on our hormones. Beneath the surface, a complex interplay of hormones regulates our metabolism, hunger and overall well-being. 

Simply said, your body’s goal is to protect you from starvation. That’s why a quick weight loss sets off an alarm (in the form of hormones) to bring your weight back up.

So what hormones can years of yo-yo diets affect? And what should you do instead?  Let’s break it down. 

Dieting Affects Your The Hunger Hormones: Ghrelin & Leptin

Ghrelin & leptin are like the yin and yang of hunger regulation. Leptin signals fullness to the brain, while ghrelin stimulates hunger. 

After doing a diet you may notice you can’t stop thinking about food – this is because of our friend ghrelin. Ghrelin is often referred to as the hunger hormone because it signals the brain it is time to eat. It is released in the bloodstream from the stomach when the stomach is empty, then travels to the brain, where it interacts with receptors to stimulate the sensation of hunger and increase food-seeking behavior (this now is pretty simple…like scanning the inside of an open refrigerator). It tends to rise before meals and decrease after eating, helping to naturally regulate our eating patterns. BUT ghrelin doesn’t only increase when your stomach is empty – it also surges when you lose weight causing persistent hunger that can lead to overeating and binging, making it extremely difficult to sustain your lower weight post diet.

Then once you start eating, it feels impossible to stop (sound familiar??) and this is because of our friend leptin. Leptin is often referred to as the satiety hormone because it signals the brain when the body has had enough food to eat and is satisfied. When leptin levels are high, it tells your brain there is enough energy stored in the body. This then leads to a reduction in appetite. Great! However, as your fat stores decrease (like through dieting), so does leptin, making it challenging to understand when to stop eating. Also, when leptin drops after weight loss, our calorie burn does too – this means that to maintain a lower weight, you need to consume fewer and fewer calories because of a slowed metabolism. 

The takeaway: When  you diet and lose weight quickly, you will feel hungrier and less satisfied. This hormonal tug of war can make continued dieting challenging, as your body fights to maintain its set point. 

Dieting Affects The Stress Hormone: Cortisol

Cortisol plays a crucial role in the body’s response to stress. When your body keeps cranking out extra cortisol for a long time, especially due to ongoing stress, it can start causing health problems and weight gain. 

When you diet, especially if you’re experiencing constant hunger or restricting (we are especially looking at you intermittent fasting), cortisol levels can rise. One research study even shows that tracking your calories increases perceived stress! Elevated cortisol levels can lead to increased belly fat and muscle loss. Here are some other signs that your cortisol levels might be running high: weak immune system, stomach troubles, feeling anxious or depressed, sleep problems, skin woes, hormonal imbalances, and heart health concerns. 

The following increase cortisol in the body:

  • Prolonged calorie restriction (dieting)
  • Extended periods of fasting
  • Constantly worrying about and tracking food
  • Excessive exercising 
  • Poorly balanced diet
  • Rapid weight loss
  • Not prioritizing sleep (i.e. exercising in the morning instead of getting enough sleep)

The takeaway: Restricting foods/calories/macros and over exercising in an unhealthy way may be leading to an increase in your weight. 

Dieting Affects The Digestive Hormone: CCK (cholecystokinin) 

When we talk about staying full after meals, we like to think about our friend, CCK. CCK is a hormone that works to regulate digestion and your appetite. When food enters the small intestine, CCK is released, sending signals to the brain to decrease hunger and increase a feeling of fullness. It also slows down the emptying of stomach contents (which is good for staying full, and better absorbing nutrients). Over time the body may adapt to prolonged calorie restriction, and this can cause CCK levels to decrease, making it harder to control food intake and maintain a weight loss.  

The takeaway: Dieting disrupts  the hormones that make you feel full between meals, and instead can make your stomach empty faster making you feel hungry more often. 

So what should you focus on instead of dieting?

Remember that your body is a complex system, and drastic diet changes can disrupt its delicate hormonal balance. Our bodies are very smart, and at the end of the day it just wants to prevent you from starving to death and wants to be fueled appropriately!

Instead of pursuing quick fixes or fad diets, focus on making gradual sustainable changes to your eating habits that promote overall health while maintaining hormonal harmony. 

Ready to find what overall health looks like for you? Set up a 15 minute discovery call with our registered dietitians to learn more about what it would look like to work together!

-Written by Christina Fogarty, MS, RDN, LDN. CDCES

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