We have been told for decades that losing weight was simple: eat fewer calories and exercise more so that you burn more calories than you consume.

Right.

If losing weight (and keeping it off) was simple, don’t you think that we would all be slender? But those of us who have struggled with weight loss, those of us who have lost weight only to put it all back on again—sometimes with interest—have long suspected that weight loss and sustaining healthy weight is not so simple as we have been led to believe.

Recent research has shown that there is indeed more than meets the eye when it comes to losing weight. Here are a few of those recent findings:

1. The Role of Stress. Researchers at the University of Pennsylvania found that stressed-out mice that had a history of quick weight loss due to dieting (imposed by the researchers, not by the mice) ate more high-fat foods than stressed mice that had not been made to diet. The study found that the stressed dieters had higher levels of the stress hormone corticosterone, and were more likely to exhibit “depressive” behavior than their non-dieting brethren. Even after the dieting mice were allowed to eat as much as they desired and had returned to normal weights, the changes in their brains respond to stress persisted.

Lesson Learned: while this study has not yet been tried on human subjects, it indicates there may be a link between quick weight-loss diets and a permanent change in the way the brain responds to stress. This may explain why so many people become “yo-yo” dieters, losing and gaining weight over and over again.

2.  Weight Loss Reduces Risk of Cancer. Moderate weight loss can reduce levels of inflammation that have been linked to the development of certain cancers, according to a study published in the May 1, 2012 issue of Cancer Research. The study was done on a group of post-menopausal women whose goal was to lose 10% of their body weight. During the one-year study, cancer-reactive protein levels dropped by about 36% in the women who only dieted, and about 42% in women who dieted and exercised. The researchers said that obesity drives inflammation, and inflammation drives the development of cancers, particularly cancers of the breast, lung, colon, and endometrial cancer.

Lesson Learned: Even modest weight loss will reduce the risk of some common cancers. Diet and exercise combined are the most effective ways to lose weight.

3.     Not All Calories Are Equal. A 2011 study at Harvard University showed that calories from potatoes (especially French fries, of course), red meat, and soda will cause more weight gain than the same number of calories consumed by eating fruits, vegetables, whole grains, poultry or fish. The study followed 120,000 non-obese, healthy Americans for up to 20 years.

Lesson Learned: It’s not just how much you eat—it’s also what you eat. Potatoes, sugary drinks, red meats, and refined carbohydrates (such as sugar, corn syrup, and white flour) will put on more poundage than fish, fowl, fruits, vegetables and whole grains.

4.     Sleeping Helps Lose—or Gain—Weight. The same study from Harvard found that study participants who slept less than six hours or more than eight hours a night gained more weight during each study period than those sleeping around seven hours a night. According to Michael Breus, PhD, author of “Beauty Sleep,” sleep deprivation increases levels of the hormone ghrelin, which stimulates appetite, and reduces levels of leptin, which tells us when to stop eating.

Lesson Learned: Aim at getting about 7.5 hours of sleep a night to avoid creeping weight gain.

5.     You Can Predict When Willpower Is Low. Every dieter has experienced this scenario: You are invited to a party where you know there will be lots of yummy and fattening food. You talk to yourself firmly about sticking to the vegetable crudités. But when you get there, the food is so beautiful and delicious-looking, and all home-made, too—and you wind up eating your day’s allowance of points or calories long before it’s time to go home.

How do you know when your willpower is going to let you down? If you monitor your heart rate variability (HRV), you can predict when your willpower is strong—or weak. When HRV levels are high, so is your will to resist. When HRV is low, your willpower will be low, as well. So if you monitor your willpower before that party and see it’s down in the dumps, you can give it a helping hand. You could eat before you go to the party, for instance. Or you could decide to stay home and avoid temptation altogether. HRV can be measured easily at home or on the go with SweetBeat™, an iPhone app, plus a compatible heart monitor (widely available in sporting goods stores or at http://sweetwaterhrv.com/store.html).

Lesson Learned: Willpower and HRV are tightly coupled. When HRV is low, don’t put yourself in a position where you know you will be tempted to go off the diet. The more we learn about weight loss, the more likely it is that we will be successful at it. Losing weight is hard; make it a little easier by using real data to give yourself a break.