Let’s take a look at the impact that being overweight has on cortisol, for example. Research presented by Deakin University in Australia showed that after consuming a meal, overweight individuals secreted radically higher levels of the stress hormone cortisol. People with a healthy weight showed a 5 percent increase in cortisol levels after consuming a meal, while overweight and obese individuals’ cortisol levels increased by a whopping 51 percent! These high cortisol levels translate to higher blood sugar, lower insulin sensitivity, and increased levels of inflammation.