The truth is, despite the popularity of low-carb diets, which often send the message that we should drastically cut back on this food group, carbohydrates are some of the most important things we consume. They are key to regulating blood sugar and providing energy throughout our bodies. Without them, our bodies will rely on protein, breaking it down for energy instead of using it in its preferred role of growing and maintaining tissues.
What's more, eating the "right" kinds of carbs can keep us healthier.
"The people who live the longest, healthiest lives -- who have the lowest rates of diabetes, heart disease and cancer -- their diets are all rich in healthy carbs, including beans, legumes, whole grains and fruit," said Tamara Duker Freuman, a New York City-based registered dietitian.
And so there's nothing wrong with a pasta meal (though whole grain is preferred) or even a sandwich on whole-wheat bread for lunch every day. Simply, the problem is not that we consume carbs; it's that we often consume the wrong kinds of carbs -- and very large portions of them.
Processed carbs are problem carbs
Highly processed carbs -- white bread, sugary cereal, white rice, regular pasta and bagels, for example -- produce rapid rises and drops in blood sugar, which can lead to weight gain. They also can lead to something called metabolic syndrome, which is associated with an increased risk for heart disease, stroke and diabetes.
Metabolic syndrome is "the combination of high triglycerides and low HDL cholesterol, insulin resistance and obesity," explained Dr. David Ludwig, professor of nutrition at the Harvard T.H. Chan School of Public Health. "And processed carbs are the main dietary drivers." Studies show that "processed carbs top the list for weight gain and diabetes risk," he said.
The tricky part is that the more processed, refined carbs we eat, the more we crave. And so it seems almost impossible to get off the carb-craving hamster wheel.
According to Ludwig, who wrote the book "Always Hungry? Conquer Cravings, Retrain Your Fat Cells, and Lose Weight Permanently," cravings have to do with our consumption of these highly processed, "fast-acting" carbs, which he says are not fundamentally different from sugar, in the biological sense. White bread or any other processed carbohydrate will melt into glucose very quickly -- and so like sugar, it raises blood sugar at a faster rate than slower-digesting carbs that are less processed and higher in fiber. The problem is, that rapid spike in blood sugar is eventually followed by a crash.
Insulin: Miracle-Gro for fat cells
According to Ludwig, what drives most carb cravings is not the taste of the foods per se but rather a biological urge to eat something to restore your blood sugar. And it has to do with the hormone insulin. "Processed carbs cause more insulin secretion, calorie for calorie, than any food," he said.
When you eat processed carbs, blood sugar rises rapidly, and insulin quickly follows, directing incoming calories into liver, muscle and fat cells. But of these, only fat cells have virtually limitless ability to store calories, and too many get trapped there, according to Ludwig. A short while later, the calories in the bloodstream are low, and the body runs out of available fuel, making you hungry too soon after the meal.
In essence, when fat cells get too much energy, there's not enough to fuel the brain, which is constantly monitoring the calories in your blood. "When (the brain) sees calories are dropping, it triggers hunger and cravings," Ludwig said.
And it all relates back to that initial insulin response. "Insulin is the Miracle-Gro for fat cells," he said. "When fat cells grow, we get hungry." And so the cycle repeats, eventually causing weight gain.
How to break carb cravings
Nutrition experts say that breaking carb cravings is not about getting rid of carbs entirely but rather cutting back on highly processed fast-acting carbs and eating more high-quality ones that are high in fiber and low in added sugars, such as beans, whole grains, fruit and vegetables. If you don't know how to get started, this plan can help:
1. Cut out all starchy carbs for one week. This includes all pasta, bread, rice, bagels and potatoes, as well as pizza, crackers, pretzels, chips, cookies and cake.
By cutting starchy carbs and replacing them with foods that have a more modest impact on blood sugar, you can achieve more steady blood sugar control and better manage your cravings, according to Freuman.
A day might include egg whites and cheese with berries for breakfast, yogurt for a snack, a grilled chicken salad with beans for lunch, an apple for a snack and a piece of fish and veggies for dinner.
2. Slash the sugary carbs too, including candy and sugar-sweetened beverages. These sugary carbs rapidly flood the bloodstream, providing lots of sugar without any added nutrition.
3. Add some fat. "Many high-fat foods are luscious and do not cause an insulin release, so they keep your blood sugar much more stable," Ludwig said. Examples include nuts, nut butters, avocado, olive oil, dark chocolate and full-fat dairy. "When you are eating them, you don't miss the processed carbs at all!"
4. After the first week, you can gradually add back high-quality starchy carbs, starting with breakfast.
"Research in a variety of populations has shown that eating carbs at breakfast seems to dampen the blood sugar effect of eating carbs at lunch," Freuman said. What this means is that on a day that you skip breakfast, you may be more likely to have a blood sugar spike after eating a carb-rich lunch, compared with a day when you eat breakfast but have the same lunch. In other words, "don't skip breakfast, and don't skip carbs at breakfast," Freuman said.
High-quality carbs -- including minimally processed grains, along with non-starchy vegetables, whole fruits and beans -- are the ones to choose. They are delicious and slower-digesting, thanks to the way they are naturally packaged, Ludwig said. "If you eat wheat berries, your body has to digest the intact grain kernel, and that's a slow process. But if you mill it and turn it into flour, now that whole package has been broken. Too much of these 'naked carbs' (stripped of their bran and germ, which contain nutrients) will cause metabolic problems for most people."
Breakfast examples with high-quality carbs include steel-cut oats with nuts, seeds and cinnamon; rye crisp bread with scrambled eggs and berries; or Greek yogurt topped with fruit. Freuman recommends beans at breakfast too, "as in a Mexican breakfast with eggs, beans, avocado and salsa."
5. After the second week, you can add back high-quality starchy carbs (i.e. minimally processed grains) to lunch. Good lunch examples include a chickpea or quinoa salad, bean or lentil soups, mushroom barley soup or a sandwich with whole-grain bread. Whole-wheat pasta or chickpea pasta is a good choice too, according to Freuman, though it should take up only about a quarter of the plate, to allow room for veggies and protein.
For the longer term
6. Continue to skip starchy carbs at dinner. "At dinner, when we eat carbs, we are much more likely to have a blood sugar spike and to store that food energy as fat versus having it available for useable energy," Freuman said.
"The metabolic response to a carbier meal at night is less favorable than when we eat carbs earlier in the day, so if there is ever one meal that you want eat low-carb, it's dinner ... and if you want to include them, choose wisely and keep the portions low," she added.
7. Continue to limit refined carbs, such as white bread and white rice. It might be difficult to forgo white basmati rice, pizza or sushi entirely, but limit these foods to a few times per week.
8. Continue to avoid foods high in added sugars. If you have a sweet tooth, limit treats to 100 to 150 calories per day, depending on your goals.
And note that anyone with a medical issue should always consult their doctor before starting a new diet plan.