The Science Behind Weight Loss
Your Body’s Response to Weight Loss Makes It Hard to Maintain Your ProgressThe tug-of-war of weight management
Losing weight and maintaining it is hard because of how the body responds to weight loss: After losing weight, the body tries to put it back on. While healthy eating and increased physical activity are important, for many people they may not be enough to keep the weight off.Following weight loss, the body’s metabolism slows down and appetite hormones change—making you feel more hungry and less full.
Did you know the brain is responsible for when and why we eat?
It’s true. All day, the nervous system, which includes the brain, receives signals about appetite from hormones that come from different parts of the body, like the stomach, intestines, and fat tissue. Both the brain and these appetite hormones contribute to what, why, and how much we eat.
For hunger
Our brain responds to appetite hormones that say we need energy—sometimes even when we don’t.
"I’m hungry. I should eat now."
For pleasure
Other times, even when we’re not hungry, signals to our brain may cause us to eat for pleasure.
"Dinner was great and I’m full, but now I want something sweet."
"My friends are going out to eat and I don’t want to feel left out."
The brain response
Reacting to hunger, pleasure, and other impulses, the brain works out what action to take.
"I feel hungry, but didn’t I just eat?"
"I’ll have a salad. Maybe that will take care of my hunger."
Remember the appetite hormones we talked about earlier? For people trying to lose weight and maintain it, changes in these hormones after weight loss can make things tricky.
That’s because after we lose weight by eating fewer calories, our levels of appetite hormones, including peptide YY (PYY), cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), amylin, insulin, and leptin, can change and contribute to weight regain.