The question of why it is so hard to lose weight and so easy to put it back on is one that plagues many people working hard to lose unwanted pounds and keep them off. It takes a look into the distant past to understand what is in our genetic makeup that favors weight gain.

In the days of hunter-gatherers, it was sometimes difficult to find enough to eat and there were periods of famine and starvation. The people who survived those hard times had bodies that were able to store fat efficiently when there was food and to decrease calorie burning when there was little or no food. These survivors passed their genes on to the next generation.

Thanks to your hardy ancestors, your body is “starvation-proof.” This means that when you eat fewer calories, your body responds by burning fewer calories in an attempt to keep you alive. If you severely restrict calories, you not only slow your metabolic rate (calorie burning) but also program your body to store fat more efficiently when you eat. The mind also responds to extreme calorie restriction by increasing your desire to eat and by signaling you to eat high calorie foods. All these systems work well to prevent starvation but work against weight loss in today's world of high calorie foods in large portions.

To have any chance of losing weight and keeping it off, you need to work with your body rather than against it. Your goal should be to increase your metabolic rate and not send starvation messages to your body and mind. Here are some ways to do that:

Eat enough calories. Do not eat fewer calories than needed for your Basal Metabolic Rate. To determine the approximate number of calories you need each day for your BMR, multiply your healthy weight by 10. For example, a woman who would weigh 120 pounds (if she did not have excess body fat) needs about 1,200 calories for her BMR. If she eats fewer than 1200 calories, she will slow down her metabolic rate. By undereating, she also is more likely to crave high fat, high calorie foods.

Build muscles. Resistance training, using weights, exercise bands or other exercise equipment, increases muscle cells, which burn far more calories than fat cells.

Do at least 30 minutes of physical activity daily. Aerobic activity, which increases your heart rate and breathing, increases your metabolic rate while you do it and for some time afterwards.

Eat breakfast. Skipping breakfast signals the start of a famine and slows down your metabolic rate for the rest of the day. In addition, breakfast skippers tend to overeat in the evening and then not feel like eating breakfast in the morning.

Eat every four to five hours during the day. Going longer than five hours without eating during the day is a signal to your body that there is no food available. The body responds by burning fewer calories.

Limit fat in foods. The fat your body stores comes from the fat you eat more than from the carbohydrate or protein you eat. The more fat you eat, the more fat-storing enzyme is produced by fat cells. Also be aware that if you eat 100 calories of fat, your body burns only 3 calories to process and store it whereas if you eat 100 calories of carbohydrate or protein, your body uses 23 calories to process and store it. It is a fact that fat is more fattening than carbohydrates or protein.

Get enough sleep. A recent study at the University of Chicago showed that women who got less than four hours of sleep per night had a slower metabolic rate than those who slept eight hours a night.

Wellness tip of the week: Ten minutes of aerobic activity three times a day has the same health benefits as thirty minutes once a day.

Christine Gutelius, MA, RD, CDN, is a nutrition resource educator with the Eat Smart NY program at Cornell Cooperative Extension of Cayuga County.

Spinach and Tortellini Soup

Makes 4 cups

1 tablespoon oil

1 cup matchstick carrots

1/2 cup chopped onions (or green onions)

3 cloves garlic, minced

1/4 teaspoon thyme

4 cups reduced sodium chicken broth

8 ounces spinach, chopped (fresh or frozen)

8 ounces cheese tortellini (frozen or dry)

In large saucepan, heat oil over medium-high heat. Add carrots, onions, garlic and thyme. Saute 3 to 5 minutes or until onion is softened but not browned. Add broth to pan and bring to a boil. Reduce heat and simmer 10 minutes. Add spinach and continue simmering for 5 minutes. Add tortellini and follow instructions for cooking time on package (about 3-4 minutes for frozen tortellini). Stir in a dash of black pepper and serve immediately.

Note: To make this soup a main course, add chopped cooked chicken or a can of cannelloni beans.