Aside from raising insulin levels, another thing to be mindful of is that sugary foods and beverages, and refined carbs tend to be calorie-dense, yet very low in nutrients, explained Melissa Morris, an ACSM-certified exercise physiologist and nutrition and applied kinesiology professor at the University of Tampa. As an ISSN-certified sports nutritonist, Morris explained that since sugary foods don't offer the protein, fibre, and healthy fats to make us feel satiated, it's easy to over-consume them, increasing our daily calorie intake, which can lead to weight gain and belly fat.
High levels of insulin in the blood also block leptin signals (the "I'm full" hormone) to the brain, explained Susan Peirce Thompson, a psychology professor with a PhD in brain and cognitive science, in a previous interview. Your brain doesn't see that you're full, so when you eat sweet treats, it thinks you're starving and increases cravings and hunger, making you eat more.