Lesson 5.2: Hormonal Changes after Weight Loss



Did some of the answers to the quiz surprise you? Being overweight is a complex condition and losing weight is more than just a matter of “moving more and eating less”. Keeping the weight off is even harder but due to current and new research and our ability to measure hormones, we have a better understanding of this. (1-4) This is one of the most important modules of this program. An understanding of these principles will help you understand your weight loss and weight maintenance journey better.

Dr Marlene Tham will try and explain the complex process of what happens to certain hormones after you lose weight.

We all know that maintaining weight loss is an important and demanding challenge but now science has discovered that weight regain has a strong hormonal basis and is not simply just lost of motivation or resumption of old habits. Research has discovered that physiological responses to weight loss trigger weight regain. (5) 

After weight loss, the changes to the levels of circulating hormones involved in homeostasis (defined as the natural regulation of body weight that keeps our body balanced and in equilibrium) occurs which causes increased hunger and weight regain after diet-induced weight loss. Our body is a very clever and adaptive organ that keeps us alive in times of famine and crisis, but it works against weight loss maintenance by regulating the peripheral hormones released by the gastro-intestinal tract, pancreas and fat and its interaction to the hypothalamus ( a part of the brain that links the nervous and hormonal system). Our body does not like any external changes that interrupts its equilibrium and this includes weight loss.

What are these hormones?

Here are some of the more well-known hormones that influence appetite, hunger, and satiety.

Hormone Effects
Cholecystokinin (CCK) Released in the small intestine when fats and proteins are eaten. Receptors that respond to CCK are not only found in the gut but also in the brain. In the brain CCK depresses hunger, meaning the more CCK you have floating around the less hungry you are, and the less you’re likely to eat. This is why a lower-carb, higher-protein, higher-fat diet tends to make people feel fuller longer.
Glucagon-like peptide-1
Delays stomach emptying time that may make you feel more full.
Gastric inhibitory polypeptide YY
Secreted by the small bowel and colon in response to food. Inhibits hunger.
Leptin  Mostly released by fat; decreases hunger. If you want to lose weight you’d want to have more leptin.
Ghrelin  Made mostly in the stomach; acts on the brain (hypothalamus) to stimulate hunger. If you want to lose weight, you want less ghrelin.


The ideal hormone combination to suppress appetite and help you lose weight would be:

  • more CCK, GLP-1, PYY, and leptin
  • less ghrelin

Hormones Diagram

Some medications are able to manipulate these hormones and as a result are able to reduce hunger and increase satiety. Some are available in tablet form and others as an injection. There is a new injection which is a GLP-1 analogue which mimics the hormone and is now available worldwide. This is something you could discuss with your doctor. What does this all mean? It means that our body does not want us to stay at the weight we have become through weight loss and attempts to push us back to our original weight through hunger (increased food intake) and weight regain (reducing energy expenditure).  It is through these mechanisms that the human race has not become extinct and has survived through the ages. This is discussed more in the next lesson on set points.

Back to: Redefine™ CBT Weight Loss Program > Module 5: Hormones and Weight Gain