Americans spend $33 billion a year trying to lose weight, but even if they're successful dropping a few pounds, 95 percent will put it back on.
Now, the diet industry is pouring their research dollars into the science of satiety -- which researches foods that naturally make you feel full.
Scientists are learning more about a hunger hormone called ghrelin. When you're hungry, this hormone is secreted in your stomach and intestines and sends a message to your brain to say it's time to eat.
Nicole Beland, a senior contributor at Women's Health magazine, says you can suppress ghrelin by eating certain foods, so you will then feel full. Carbohydrates and lean protein have been found to slow the production of ghrelin, while foods that are high in fat do not.
When you eat something that is high in protein, carbohydrates or fiber, after 20 minutes the food passes through your stomach to your lower intestines where other hormones are released that tell your brain it's time to stop eating. Then your stomach literally expands when you're full, which is called the gastric stretch, sending another signal to your brain that you are satisfied with your meal.
While more still needs to be learned about why certain foods slow ghrelin, there are some guidelines you can follow. Beland offers this comparison of some basic foods to show which choices are more likely to leave you feeling full:
Baked potato, mashed potato or French fries? Studies show that white potatoes are one of the most satisfying foods. The non-fried potato is the better choice because fries have a high fat content. The carbohydrates and fiber of white potatoes stay in your digestive system longer and leave you feeling more full than fat does.
Juicy hamburger or lean steak? Lean steak because lean protein is the second best option for satisfying your hunger.
Cod and flounder, or salmon and tuna? Stick with the white fish. In general, the lighter the color of the fish the less fat it contains and the more satisfied it will leave you at the end of the meal. White fish usually has one to two grams of fat per four ounces; pale-colored fish such as pink salmon, catfish and swordfish has three to six grams of fat per four ounces; and dark fish like mackerel, rainbow trout and red tuna range from eight to 16 grams of fat per four ounces.
Cream of broccoli or lentil soup? Lentil soup, because beans are a great source of fiber and protein. Protein takes longer to digest than fat, and fiber adds a lot of bulk, which helps produce the gastric stretching that makes us feel like we can't eat another bite. Even the broth in lentil soup will satisfy more than the fatty cream base of cream of broccoli. While broccoli is also a good form of fiber, lentils beat it hands down.
Before you get started, there are a few other considerations to help those ghrelin-suppressing foods do their magic. For starters, remember to be patient. Wait 20 minutes after eating your first serving before deciding if you need a second helping or dessert. It takes time for food to start digesting and make it down into your lower intestine so you won't know if you're truly hungry until you've digested that first course.
It's also important to time your meals carefully. The ghrelin factor comes into play because the hormone will spike if you don't eat when you're accustomed to having a meal.
Space your meals evenly apart to help keep ghrelin levels from rising. If they're not spaced evenly apart, nudge them closer to that goal in 15-minute increments -- so if you usually eat lunch at 12 and dinner at 7, eat lunch at 12:15 tomorrow, 12:30 the next day and so on until there's an equal amount of time between each meal.