Why is it so hard to lose weight and keep it off? One reason may be that your own body doesn’t want you to lose weight. Everyone has a weight that their body maintains without a lot of effort.

Despite Americans spending billions of dollars on weight loss drugs, diet programs and gym memberships, our nation is seeing little success in our obesity battle. It seems that we are all trying to lose weight but just aren’t having much luck. Statistics on weight loss success are pretty depressing. The New England Journal of Medicine estimates that 80 percent of dieters regain all of their lost weight (and sometimes more) in just one to two years.

Why is it so hard to lose weight and keep it off? One reason may be that your own body doesn’t want you to lose weight. Everyone has a weight that their body maintains without a lot of effort. This weight is often referred to as the body’s set point. Your body fights to maintain this weight, which is usually in a 10-to-20-pound range. Unfortunately, this number may be higher than you want. Every person’s set point is different and can change based on age, the number of previous weight loss attempts, changes in muscle mass, activity level changes and hormone changes, such as with pregnancy, menopause or decline in testosterone.

Gradual weight gain also can increase your set point weight. Just an extra 100 calories a day more than you burn will cause weight gain so gradual that your body adapts to its new normal weight. It is much easier for the body to accept weight gain than weight loss.

Why does your body like extra weight? Our genes are programmed for survival, and to survive, fat storage is essential. Fat stores help ensure our ability to reproduce and are insurance against famine. Your body will not only fight to prevent weight loss but also to return to a previous higher weight. One way your body does this is through responding to weight loss with a slower metabolism. This trick lets your body conserve energy so you burn fewer calories. You may notice being sleepier or feeling colder when you are dieting. This is your body conserving energy.

Your body also fights weight loss by producing hormones that encourage the body to eat more. Leptin is a satiety hormone produced by fat cells. It tells the brain when you are full. As you lose weight (fat), less leptin is produced, so the brain isn’t getting the message that you are full. This hormone level stays low even after weight loss, so the brain becomes less aware of how much you have eaten. Ghrelin is another hormone associated with weight and appetite. It is produced in the stomach and signals the brain when it is time to refuel. As you lose weight, the amount of this hormone goes up and stays up after weight loss, making it harder for you to eat less.

Also working against you is the fact that it takes less energy to move a lighter body. This means that you will burn fewer and fewer calories as you drop pounds. Meanwhile, your hormones will tell you to eat more. Your body eventually becomes resistant to the leptin messages resulting in a constant battle between hormones and brain. All of this adds up to mean someone who drops from 200 pounds to 150 pounds will burn fewer calories than someone else who is 150 pounds but has never weighed more — and the person who has lost weight will likely feel hungrier.

So, other than never gaining weight in the first place, how can you lower your body’s set point and permanently lose weight? Following is some tried-and-true advice from the 20 percent who managed to keep the weight off permanently.

1. Prepare for a total lifestyle change. Returning to your former “normal” way of eating isn’t an option if you want to keep the weight off. After all, that is how you gained the weight.

2. Cut out refined carbs, such as white bread, cereals, pasta and pastries. Refined carbs have little fiber and therefore increase insulin levels and promote fat storage. Highly palatable foods, such as sweets, blunt leptin and ghrelin messages, making it super easy to overeat.

3. Lose the weight slowly. You will be most likely to keep the weight off if you lose just five to 10 percent of your body weight and then maintain that weight for two or three months before attempting to lose more. If you have a lot of weight to lose, keep repeating that cycle rather than continually dieting.

4. Cultivate gut bacteria associated with leaner bodies. Eat more fermented and cultured foods, such as kefir and yogurt. Increase the fiber in your diet to help introduce healthful microbes. Avoid artificial sweeteners because these are associated with unhealthy gut microbes that contribute to obesity. Avoid “diet” foods altogether because they are not as satisfying as the real thing and often contain ingredients that support unhealthy gut bacteria.

5. Try zigzag dieting to keep the body from going into survival mode. Instead of following a reduced-calorie diet all of the time, try eating fewer calories every other day. For example, you might alternate between 1,200 calories per day and 1,800 calories per day.

6. Be aware of your environment. Hunger is often not the reason that we eat. We are surrounded by oversized portions and tempting food, and we often eat while our minds are busy with something else. Find ways to overcome triggers that make you eat when you are not really hungry.

7. Include strength training in your exercise program. Muscle burns more calories than fat, so building more muscle will help with weight loss.

Here’s to successful weight loss in 2017!

Anita Marlay, R.D., L.D., is a dietitian in the Cardiopulmonary Rehab department at Lake Regional Health System in Osage Beach, Mo.