Not many of us can be on-target with our eating and exercising every single day of the year. It’s mentally taxing. Working out and eating right all the time can leave you itching for a day of sloth and gluttony, which is normal operating procedure for most humans. That’s why cheat meals and off days are important: They help psychologically (with deprivation) and physiologically (with rest and recovery).

But while we've all indulged in the occasional cheat day, it’s important to keep your bodyweight fairly consistent—or, if you're trying to lose weight, to do so gradually. We know it's tempting to drop all of your body fat all at once. But losing weight too quickly or too slowly can create dramatic changes within the body—and your body can't always recover, according to recent research from Stanford University Medical Center.

The small study, which was initiated to investigate people with pre-diabetic symptoms, looked at baseline levels of gene expression, protein production, microbiome, and genome in 23 subjects. Some were insulin-resistant (who showed unusual levels of inflammation), while others were still insulin-sensitive (and did not show inflammation).

The researchers then put both groups of people on a high-calorie diet for 30 days. People in both groups gained an average of 6lbs—and both started to show signs of inflammation. Both groups also started to show shifts in their gut bacteria, as well as gene expression related to heart failure.

Thankfully, when the excess weight was dropped, these bodily systems went back to mostly normal fairly quickly, said senior author Michael Snyder, Ph.D., a Stanford genetics professor.

"The goal here was to characterize what happens during weight gain and loss at a level that no one has ever done before…In the end, we literally made billions of measurements." And the results confirmed what we know about the human body, he said: “It's a whole system, not just a few isolated components, so there are system-wide changes when people gain weight."