The Pros and Cons of Today’s Most Popular Diets

Rapid weight-loss diets may produce quick results, but most are hard to stick to over time, so the pounds often come back. Some can also be unhealthy – especially diets that limit important nutrients by restricting certain food groups. Experts say that safe, lasting weight loss involves realistic long-term goals, watching calories, and getting nutrients from all of the food groups.

Research shows that interest in rapid weight-loss diets, sometimes called fad diets, has increased over the past two decades. Most of these diets share some common features, such as:

  • Promising fast weight loss
  • Focusing on one type of food, or eliminating one or more food groups
  • Few or no physical activity guidelines
  • Promoting short-term changes rather than lifelong healthy habits
  • Being hard to stick to over a long period of time
  • Questionable nutritional value

Diet and nutrition specialists say that some of the popular diets that promise fast and easy weight loss can be useful in cases where a medical condition requires it. Also, they might make sense for jumpstarting weight loss before beginning a more steady, long-term eating and lifestyle plan for keeping weight off. The pros and cons of several popular diets are discussed below.

Keto Diet

A ketogenic (“keto”) diet is high in fat and low in carbohydrates (sugars). This causes the body to break down fat into molecules called ketones. Ketones circulate in the blood and become the main source of energy for many cells in the body. This diet is used to treat some types of epilepsy and is being studied for treating some types of cancer.

  • Pros: Very effective for short-term weight loss and for reducing epileptic seizures. Studies suggest it may have benefits for treating diabetes and some cancers.
  • Cons: Not enough research that proves it works and is safe over long periods. Extreme limits on carbohydrate consumption, which can cause digestive problems, headaches, and other side effects. This diet’s restriction of many healthy foods, such as fruits and grains, limits nutrient levels.

Intermittent Fasting

Intermittent fasting is an eating pattern that includes hours or days of little or no food consumption, but without limiting essential nutrients. Commonly studied versions of this diet include alternate day fasting, fasting two days each week, and strict limits on when it’s ok to eat.

  • Pros: Many dieters find it easier to not eat during parts of the day rather than following portion control and calorie restrictions all of the time. A small amount of research suggests that fasting may lower blood pressure, blood sugar, and cholesterol levels.
  • Cons: May limit intake of vitamins and minerals. Despite being effective for weight loss, little is known about long-term health effects or how easily people can stick to this diet.

Paleo Diet

Named for the Paleolithic era, when humans obtained food by hunting and gathering instead of farming and processing, this diet emphasizes lean meats, fish, vegetables, fruits, and nuts.

  • Pros: Successful weight and appetite reduction, and some positive impact on heart health
  • Cons: Limited by cost and food availability, expensive and harder to follow than some other diets. It restricts certain food groups such as dairy products, fiber-rich whole grains, and legumes (beans and peas), so this diet may have long-term negative effects on nutritional balance, such as calcium and fiber intake.

Atkins Diet

Similar to the keto diet with its focus on burning fat, the Atkins diet was modified in 2002 to the four-phase New Atkins Diet Revolution. It eliminates foods made with refined flour and sugar and restricts whole-grain foods until the final phase of the diet.

  • Pros: Effective for short-term weight loss, and easier to maintain than similar diets that limit fat intake
  • Cons: May decrease nutrient intake. Studies suggest that low-carbohydrate diets are unlikely to result in long-term weight loss and may lead to health problems.

Mediterranean Diet

This diet follows the traditional eating habits and lifestyle in countries along the Mediterranean Sea. Many different food cultures exist in that region, but there are many common features, including focusing on fruits, vegetables, whole grains, beans, nuts, and heart-healthy fats, while limiting dairy products, red meat, highly processed foods, and added sugars and salt.

  • Pros: It is the most extensively studied diet to date, and research shows that it can have a preventive and therapeutic impact on many chronic health conditions. It’s especially popular among people who are interested in a healthy lifestyle and not just weight loss.
  • Cons: Can be expensive to maintain. If calories from olive oil and nuts are not carefully watched, those and other fatty foods in this diet may contribute to weight gain.

Which Plan Is Right for You?

Some people have success with popular weight-loss diets, but results vary depending on weight and height, gender, physical activity levels, lifestyle and income, and any existing health conditions. Because so many factors affect whether a diet plan is right for you, it’s important to talk to a health care provider or weight-loss specialist before choosing.

Karin Crowell, RD, LD, CDCES, a clinical dietitian with UAB Weight Loss Medicine, says the most successful diet is the one you can actually maintain.

“Sustainability is the most important factor in diets that are designed to help you lose weight and keep it off,” Crowell says. “It’s normal for people to look for a quick and easy fix, because they naturally want results right away. Some trendy diets might help you get a few pounds off in the short run. But based on behavior that medical professionals have observed in weight-loss clinics over decades, we know that most people will not or cannot stay with those diets. They may feel like they’ve failed, but the truth is that their expectations were probably not realistic to begin with.”

Crowell says weight-loss expectations are more likely to be realistic if they’re based on long-term diet plans that most people can maintain.

“We help our patients create plans they can stick to, and usually that goes back to calories in versus calories out,” Crowell says. “To lose weight, you need to be burning more calories than you consume. We measure resting energy expenditure. If we see that you are burning 1,800 calories per day, then we would recommend consuming 1,300 calories per day. That 500-calorie deficit should help you lose 1-2 pounds per week. So, a plan to lose 4-6 pounds per month gives you a reasonable expectation.”

Slow and Steady

Research shows that rapid weight loss is almost never sustainable. Quick weight-loss diets often come with health risks, and any weight lost is likely to be regained when you return to your normal eating habits. However, most people can lose weight through a slow, steady process of decreasing calorie intake while taking in enough nutrients and increasing physical activity. It’s possible to cut calories without eating less nutritious food. The key is to eat foods that will fill you up without taking in too many calories.

A healthy diet can include reasonable amounts of fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products. It also can include a variety of protein foods such as seafood, lean meats and poultry, eggs, legumes, soy products, nuts, and seeds. A healthy diet plan also calls for limiting sodium, added sugars, saturated fats, trans fats, and cholesterol.

Diet experts agree that no food or food group is completely off limits. They advise people to choose a plan they can stick to, while emphasizing nutritional balance. Each food group plays a role in providing the body with vitamins, fiber, calcium, and other nutrients. Unless a health condition requires avoiding certain things, no food group needs to be off the table.

Diets designed for quick weight loss may be a useful choice in the short term, but long-term weight control requires a long-term eating and lifestyle plan. As with anything that affects your health, however, it’s always wise to talk to an expert before making any major diet or eating habit changes.

The UAB Weight Loss Medicine clinic helps patients lose weight and keep it off. Services include medical oversight from physicians, FDA-approved medications when appropriate, and group sessions. No physician referral is needed for any of the services. Click here to learn more.

SOURCE: National Institutes of Health

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