We'll Give It To You Straight:

Dropping 10 pounds in a month is a challenge, but one you'll have no trouble meeting if you have the right tools. A fat-burning workout routine (like Get Your Leanest Body Ever) is essential. But perhaps even more important is a diet plan that keeps you satiated and energetic enough to get through said workout! The trouble with most diets (besides the boring food lists and the inevitable hunger pangs) is that it's tricky to fi nd one that helps you drop pounds without compromising the nutritional quality of your meals-and ultimately your health and vitality.

That's why we're so keen on a low glycemic index (GI) diet, a plan based on how quickly carbohydrate-rich foods are digested and absorbed into your bloodstream. Eating too many high-GI foods-such as white bread (and other products made with white fl our), potatoes, white rice, sugary drinks, and many processed foods-will lead to excessive hunger because they pass rapidly through your system. As a result, you'll probably take in more than your body needs and still not feel satisfi ed. "In one study I conducted, participants who ate a high-GI breakfast and lunch consumed 700 more calories later in the day than those who had low-GI meals," says Harvard researcher David Ludwig, M.D., Ph.D., author of Ending the Food Fight. "Foods that break down fast may also trigger hormonal imbalances that cause you to store more of what you eat as fat."

You may have heard of the low-GI diet-the plan has been around in various forms for years. But several new studies suggest it's as close to a weight-loss magic bullet as we may ever hope to fi nd-and that it's as important for protecting your health as it is for shedding pounds. "Low-GI foods also happen to be some of the most nutritious. They're loaded with fi ber, vitamins, minerals, phytochemicals, and other disease-fi ghting compounds," says Jennie Brand-Miller, Ph.D., a professor of human nutrition at the University of Sydney in Australia. "Your cholesterol will improve, your diabetes risk will decline, and, if you have acne, your skin may clear up." And because the plan gives you that high-quality energy most low-carb diets lack, you'll actually feel pumped about hitting the gym. Ready to get started? Here's everything you need to know to make this the most successful weight-loss plan you've ever tried. Exactly What To Eat
The objective of a low-GI diet is to keep your blood sugar, or glucose, levels steady.

What does that have to do with your weight? When you eat carbs, blood glucose rises. In response, your pancreas releases the hormone insulin to transport the glucose from your bloodstream into the cells, where it can be used for energy. High-GI foods cause quick and extreme spikes in glucose levels; any excess not used by the body for fuel is stored as fat. As a consequence, the pancreas has to pump out a lot of insulin, which can result in glucose levels dipping too low, so you become hungry again very quickly. "Low-GI foods, on the other hand, release glucose into your blood slowly, so the insulin response is more gradual," says Brand-Miller. "This keeps you satiated longer and allows the body to use fat rather than glucose for fuel."

A number of factors affect GI values, including fiber content, the form of the food (baked potatoes rank higher on the GI scale than boiled ones), ripeness (for fruit), how long a food is cooked (al dente pasta has a lower GI score than mushy pasta), and how a food is processed (for instance, some brands of wholewheat bread fall lower on the GI scale than others because the grain is milled less). Yes, it can get confusing, so consult the list at shape.com/meltdown and follow these general guidelines:

• Make whole grains, vegetables, fruit, and beans the center of meals
  These foods have a low-GI value, and in the case of non-starchy vegetables, a GI value of 0.

• Add in lean protein
  Meat, fish, poultry, cheese, and tofu have no carbs, so GI doesn't apply. And protein is satiating, so eat it at meals to keep you full longer.

• Be careful with snacks
  They tend to be the only foods we eat by themselves. "A lowfat fruit yogurt, a sugary granola bar, or a couple of crackers can send blood glucose soaring and then crashing," says Margaret Lovesky, R.D., a dietitian at Children's Hospital Boston. Choose low-GI foods for snacks (like raw vegetables and hummus or an apple). If a high-GI food is your only choice, pair it with protein or healthy fat (e.g., have a few crackers and an ounce of cheese or a little peanut butter).

• Eat several small meals
  Spacing out your calories is key to keeping blood sugar levels on an even keel. "If you take in the majority of your calories at one or two sittings, your blood glucose levels will fl uctuate more, even if you're sticking to low-GI foods," says Lovesky.

• Don't rely only on the GI
  Foods like pepperoni pizza, pound cake, and potato chips rank low on the GI scale. But this doesn't make them good for weight loss, of course. You still have to take calories into account and consider what the food contributes nutritionally to your diet. Save them for the occasional treat. And likewise, don't nix healthy foods that have a high GI value, such as watermelon, beets, and winter squash. "These foods are low in carbs, so when you eat them with other foods, they have very little effect on your overall glucose response," says Brand-Miller.
  Shape asked Lovesky, who provides nutrition counseling to participants in Ludwig's studies, to give us a customized low-GI plan that will help you drop 10 pounds this month. We've given you a sample day (see One Day on a low-GI diet); the full seven-day diet can be found at shape.com/meltdown (start the plan again at the end of week one and follow it all month long). It supplies 1,600 calories a day- probably 500 to 700 fewer than you're eating now. "Still, you won't be starving," she says. "You might actually feel fuller than you usually do." Don't be tempted to skip meals in an effort to speed your results, though. Cutting back too far on calories can send your metabolism plunging. Plus, you'll be doing an intense workout routine, so you'll need the energy.

How GI Helps With Weight Loss
You'll be more likely to stick with this diet than other plans. Although it's low in calories, the food is filling-and doesn't taste like diet food. Plus, you'll be able to avoid those late afternoon energy slumps that make you reach for sugary snacks.

It's not just one or two studies that show the benefi ts of a low-GI diet. A review of 20 studies from Tufts University confirms that low- GI diets are more satiating than those at the other end of the index. "In addition to preventing insulin spikes, low-GI foods stay in your system long enough to reach the lower part of the small intestine. That's where many appetitesuppressing hormones are released," says Brand-Miller. And although your metabolism dips any time you cut calories to lose weight, a GI diet has less of an effect than other plans. One study found that metabolism declined 11 percent in people following a lowfat diet, but just 6 percent in people on a low-GI one. "When blood glucose stays steady, your body is less likely to assume it's starving," says Ludwig, "and therefore less likely to slow metabolism to hang on to every calorie it can."

The Health Benefits
A big drawback of most weight-loss programs, especially those with extensive do not eat lists, is that healthy, nutrient-rich foods are often eliminated from your diet.

The result: a diet that might provide quick, short-term weight loss but puts your health at risk. "It's not even worth dropping pounds on some of these extreme plans. For instance, if you lose weight but your cholesterol goes up, you've simply swapped one heartdisease risk factor for another," says Brand-Miller. A low-GI diet steers you toward a wide range of healthy foods that can help your heart. "Women on a low- GI diet lowered their cholesterol by about 10 percent in just two months," says Simin Liu, M.D., a professor of epidemiology at UCLA. "They also seem to have less C-reactive protein, an inflammatory compound that's been linked to heart attacks."

Slow-release carbs may also help your body in other ways. A Harvard study found that women are about half as likely to develop type 2 diabetes on a low-GI diet-especially one that's high in fi ber. Low-GI diets may even protect against cancer. A recent British study noted a 55 percent increase in breast cancer risk for every 5 percent of calories that came from high-GI carbs. So at the end of this month, when you step on the scale, don't just celebrate what you've done for your fi gure, congratulate yourself for the way you've improved your health. One Day On A Low-GI Diet
This is what 1,600 calories a day looks like on this eating plan. The combination of low-GI foods and lean protein at every meal will keep you satisfied. If you do feel hungry, add in the extra 100-calorie snack.

Breakfast

• Greek egg scramble (3 egg whites; ¾ cup red onions, tomatoes, and olives; 2 tbsp. feta cheese)
• Pomegranate (1)

Snack

• String cheese (1)

Lunch

• Pasta salad (3 oz. grilled chicken, 1 cup grilled eggplant and roasted red peppers, ½ cup chickpeas, 1 cup pasta, 2 tbsp. Italian dressing)

Snack

Celery sticks with peanut butter (8 celery sticks spread with 2 tbsp. all-natural peanut butter)

Dinner

• Turkey chili (3 oz. ground turkey, ½ cup kidney beans, ½ cup onion, ½ cup tomato sauce, chili seasoning). Top with ¼ cup reduced-fat shredded cheddar cheese
• Strawberry-spinach salad (2 cups spinach, ½ cup strawberries, 2 tbsp. pistachios, 2 tbsp. balsamic vinaigrette)

100-Calorie Snack
(optional)

• Baked apple with cinnamon (1) (Find the entire seven-day eating plan at shape.com/meltdown.)