The Carbohydrate Controversy

Mar. 16, 2021

For decades, carbohydrates have been a source of controversy in the world of weight management. As fad diets and food trends come and go, we are often left confused about what we should really be eating.

During National Nutrition Month, answers to common questions about carbohydrates — both good and bad — are provided by Haylee Hannah, RD, registered dietitian and certified specialist in obesity and weight management at the UC Health Weight Loss Center.

What are carbohydrates?

Along with protein, fat and alcohol, carbohydrates are considered one of the “macronutrients.” Carbohydrates are a source of energy for the body, providing 4 calories per gram.

Found in a wide range of foods, carbohydrates are often described as “simple” or “complex,” and can be further classified as sugars, starches and fibers, depending on the length and structure of the carbohydrate molecule. Sugars and starches can be broken down by our bodies and used as energy. Fiber cannot be broken down for energy, but has other important functions in the body.

Most foods that we eat contain at least some carbohydrates. Significant sources include bread, pasta, rice and other grains, milk and yogurt, fruits, vegetables, beans and, of course, foods with added sugars such as sweets and sugary beverages. 

What happens when we eat carbohydrates?

When you eat carbohydrates, your body breaks them down into glucose or “sugar” molecules, which are absorbed into the bloodstream. As glucose levels rise in your body, insulin is released from the pancreas, which is necessary to move glucose from the blood into the cells where it can be used as energy or stored for later use. Carbohydrates that are not needed for energy right away are first stored in the liver and muscle for later use in the form of glycogen. Excessive intake of carbohydrates will be converted and stored as fat.

How many do we need?

A common question that dietitians at the UC Health Weight Loss Center are asked is, “How many grams of carbohydrates should I eat to lose weight?” and “Should I be tracking my macros?” The answer is that there is truly no one-size-fits-all approach to nutrition. Studies have shown that people can meet their nutrition needs and achieve and maintain a healthy weight at a wide range of daily carbohydrate intakes. For most people, carbohydrates comprise about 45-65% of their daily calorie intake.

What are the best carbohydrate choices?

Not all carbohydrates are created equally. Especially when trying to manage your weight, it is important to focus not only on how much to consume, but also the nutrition quality. 

Carbohydrates To Limit

These foods are often described as “empty calories,” as they provide significant calories, but have limited, if any, other important nutrients. These foods are digested very quickly and often do not keep us feeling full very long. Save these foods for special occasions, or avoid them altogether if they cause you to feel out of control with eating. Examples of ‘empty calorie’ carbohydrate foods include:

  • Highly processed grains including crackers, chips, pretzels and sweetened cereals, as well as white bread, white pasta and white rice.
  • Cookies, cakes, pastries, candy and other sweets.
  • Beverages such as sodas, sweetened tea and coffee drinks, energy drinks, fruit juices and fruit juice cocktails.

Carbohydrates To Choose Most Often

These are often called “healthy” or “nutrient-dense” carbs. High-quality carbohydrates still provide calories, however they also deliver a healthy dose of vitamins, minerals, fiber and sometimes, protein. Examples of high-quality carbohydrate foods include:

  • Whole fruits and vegetables.
  • Beans, as in chickpeas, kidney beans, black beans and lentils.
  • Whole grains, such as quinoa, farro, brown and wild rice, whole corn, bulgur, amaranth and steel-cut oats.
  • Dairy products, such as milk, yogurt and kefir (look for products with less than 10 grams of sugar per serving).

How do carbohydrates affect weight?

If you’ve ever followed a low-carb diet before, such as Atkins® or a “ketogenic” diet, also known as “keto,” you’ve undoubtedly noticed a rapid weight loss at the start of the diet, followed by rapid weight regain once carbohydrates are re-introduced. This would naturally lead one to conclude that carbs are bad and cause weight gain. However, before you vow off carbs forever, it is important to understand that this rapid weight loss and regain is largely related to water gain and loss, not fat.

Remember that we first store carbohydrates in our liver and muscle as glycogen. Glycogen’s structure is highly complex and branched, which makes it really good for soaking up water (think of cornstarch — starch is the plant’s storage form of carbohydrate). When you burn through your stored glycogen on a low-carb diet, this water is released. When you replenish your stored glycogen by eating carbohydrates, your body holds more water again. It’s a natural process, but it’s enough to drive you crazy watching the scale go up and down. Keep in mind that 1 pound of fat is about 3500 calories. So, if your weight went up a pound overnight and you know you didn’t eat 3500 extra calories, take a deep breath. Your weight will fluctuate day to day (even hour to hour) due to water gains and loss.

Though glycogen can explain the rapid fluctuations in weight, there is no doubt that people can lose significant amounts of fat on low-carbohydrate diets. A large part of the success with these diets is people are often eating less calories overall. Cutting out empty calorie foods such as sweets, chips, fried foods and sugary drinks is a great idea for any weight loss plan. Many find that the simplicity of low-carb diet plans improve their ability to follow them. In addition, people on low-carb diets tend to focus on higher intakes of protein, fat and vegetables, all of which are known to help with feeling full.

What happens over the long term on low-carb diets?

Numerous studies have compared weight loss outcomes among various levels of carbohydrate intakes. Most show that people lose weight faster initially on low-carbohydrate diets, but weight loss is comparable to other diets over the long term. The DIETFITS study was a large, well-designed randomized controlled trial that evaluated outcomes of a healthy low-fat diet compared to a healthy low-carb diet. Results of this study showed that after one year on the diet, there were no differences in overall weight loss between the two dietary approaches.

According to the most recent position statement by the Academy of Nutrition and Dietetics, there really is no “one-size-fits-all” approach to the best diet to promote weight loss. As long as the target reduction in calorie level is achieved, many different dietary approaches are effective. In short, the best diet is the one that you can realistically follow long-term.

Should I follow a low-carb diet?

When considering what level of carbohydrate intake is right for you, consider your health history and lifestyle. If you have a history of diabetes or have been told you are insulin-resistant, you may find that following a lower carbohydrate diet can be helpful in managing your blood sugar levels as well as your weight.

Also, consider your level of physical activity. If you participate in moderate-to-intense physical activity on a regular basis, you may find that your energy levels, performance and recovery benefit from having higher amounts of carbohydrate before, during or even after a workout.

Remember that diets work as long as you are able to follow them. Before starting any diet, ask yourself the following questions:

  • Do I see myself following this diet several years from now? If not, think about what you will gain from following this diet short term. Will you learn important lifestyle habits to help with your long-term success? Do you have a transition plan when you are ready to stop the diet? If the answer to all of these questions is no, move on.
  • Does this diet eliminate foods that have known health benefits? A common mistake with low-carbohydrate diets is focusing on eating only meats and fats, and eliminating all plant foods. This strategy is not only difficult to sustain, but lacks key nutrients that are important for health and longevity. High-fiber foods such as vegetables and small portions of fruits can fit into a low-carb plan. Avoid going to extremes with restriction.
  • Can I realistically follow this diet with my food preferences and lifestyle? For example, if you are a vegetarian, adding a low-carbohydrate element to your diet may feel especially restricting. Your diet should also not be socially isolating. Does following this meal plan make it difficult to eat with others? A sustainable diet should be adaptable in a variety of settings.

What if I’ve had bariatric surgery?

We encourage patients during active weight loss to ensure an adequate intake of protein to maintain muscle mass and manage hunger, and to aim to stay within a target calorie range to achieve and maintain a healthy weight. Beyond this, it is normal to have some variation from day to day in each macronutrient category, including carbohydrates. If you participate in high levels of physical activity, your bariatric dietitian can help you plan how to adequately fuel. Instead of focusing too closely on hitting exact numbers each day, focus on achieving an overall healthy dietary pattern that is focused on lean protein, adequate plant foods and small portions of healthy fats and whole grains.

In Summary

Low-carbohydrate diets have been a popular weight management strategy for many years. Studies have shown that this dietary approach can be successful for both weight management as well as diabetes management. It’s important to note, however, that as long as a sustained calorie reduction is achieved, people can be successful with weight loss utilizing a variety of approaches. To determine if a low-carbohydrate diet is right for you, consider your health history, food preferences and lifestyle.

Tracking with an app such as MyFitnessPal or Lose It is a proven method to help people achieve their weight management goals, and can give you a good idea of how many calories, carbohydrates and other nutrients you are consuming each day. Speak with a registered dietitian to help you customize your plan based on your health history, lifestyle and weight management goals. 

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To learn more about weight loss programs offered by the UC Health Weight Loss Center, please call 513-939-2263.