Clearing the Confusion: Diet myths and weight loss

Reviewed March 2, 2020 by Maria Barnes, Ph.D., Assistant Professor of Biochemistry and Nutrition

When it comes to dieting, it is almost impossible to open a webpage without ads flashing in our faces telling us to avoid these five foods and lose weight for good or follow this diet to lose 10 pounds in 10 days. Unfortunately, most of this is nonsense. Nutrition is not one size fits all, but using scientific facts to deconstruct some diet myths can help you reach their goals.


Myth #1: You should Cut calories for weight loss

Yes, a reduction in total calorie intake is recommended to lose weight. However, more is not always better. Cutting too many calories can actually hurt your ability to lose weight and keep it off. Extreme calorie restriction almost always will result in weight loss; however, when weight is lost this way, it is at the expense of your metabolism.

Unfortunately, this weight is almost guaranteed to come back, and then some! Our metabolism is simply defined as the process by which our bodies turn food and drink into energy (i.e., “burn calories”). A higher metabolism means more calories burned. If we restrict calories (energy), then the body has to slow down to preserve energy, which means our metabolism slows. With a slow metabolism, we don’t burn calories as efficiently, which makes it harder to lose weight. Even if some initial weight loss resulted from severe calorie restriction, a slowed metabolism makes it harder and harder to continue to lose.

“Avoid these five foods! Lose 10 pounds in 10 days without exercise!” It’s hard to avoid the barrage of bogus promises like these given our desire for instant gratification.

When regular eating resumes (and it will!), the metabolism is too slow to burn all those extra calories, and the weight creeps back on. Instead, slow and steady wins the race. It can be a struggle to be patient in our instant gratification world, but most of us would rather lose weight once and for all instead of repeatedly losing and gaining and losing and gaining.

In addition to a slowed metabolism, severe calorie restriction can lead to decreased lean muscle mass, decreased testosterone and loss of energy. The key is to cut calories enough to promote gradual weight loss (one to two pounds per week), which is about 500 calories per day. This can be done by eating less, exercising more or both. I recommend eating something every three to four hours, whether a meal or a small snack, and to always eat breakfast. Our metabolism slows overnight, and breakfast is a way to get it revved up for the day.


Myth #2: Carbohydrates make us fat

Carbohydrates’ reputation has been stomped in the mud for no good reason. But what are carbohydrates, exactly? They’re an essential part of our diet; humans cannot survive without them. They are the body’s main source of fuel and particularly important fuel for the brain. We use these macronutrients while walking around, exercising, typing emails and even sleeping.

Carbohydrates can be stored in the body as glycogen for later use but also can be stored in the body as fat — which is where carbohydrates got their bad rap. It is true that carbohydrates can make us fat, but that doesn’t mean they should be shunned from your diet. The key is knowing how much and what types of carbohydrates won’t lead to weight gain. Yes, eating a very low-carb diet will likely lead to weight loss (similar to the low-calorie diet discussed above). However, it is at the expense of one’s energy, brain function and muscle mass, and it’s very hard to maintain for the long term without negative effects on health.

To be sure, most Americans do eat too many carbohydrates, primarily in the form of sugar. Sugar-sweetened beverages are a huge culprit for added calories. In addition, large servings of grains lead to high intake of carbohydrates.

Indeed, portion size is important in weight management. The U.S.D.A. MyPlate recommendation for grain is five to eight servings per day for adults depending on your age and sex. A half cup of pasta, rice and oatmeal equal one serving of grains. Who eats a half cup of pasta? More astonishingly, one bakery bagel is equivalent to four servings of grain. You’ve almost maxed out by the end of breakfast!

The recommended intake for total carbohydrates is 45-65 percent of total calories. For a 2,000-calorie diet, this would be 225-325 grams per day.

Remember that carbohydrates are not just grains. Fruits, vegetables and dairy all have carbohydrates. Fruits and vegetables have lower carbohydrate content than grains and also provide the benefit of fiber, vitamins, minerals and antioxidants. Fill half your plate with fruits and vegetables and limit grains to one-quarter of the plate. Choose whole grains instead of processed grains whenever possible (100 percent whole wheat bread, brown rice and whole wheat pasta).


Myth #3: A fat-free diet leads to fat loss

Like carbohydrates, fat is essential for life. Our bodies need fat to provide energy and help absorb certain essential vitamins. Fat also contributes amazing flavor and texture to food. This unnecessary fear of fat can be traced back to the 1970s when Americans were told that fat in our diet makes us fat and leads to disease. Cut the food fat and cut the body fat.

Not so fast!

Taking the fat out of food leaves us with dry, cardboard-flavored food. Something has to be added back to the food to make it palatable. Sugar! Not only did typically high-fat foods become higher in sugar, but our plates changed to contain more grains, replacing meat and butter-lathered potatoes with a mountain of pasta and a nice-sized piece of garlic bread spread with margarine. Again, too many carbohydrates in the diet can lead to weight gain. As the fat intake of Americans dropped, weight continued to rise — not the result anyone expected.

Very low-fat or nonfat diets are not recommended for weight loss and can actually have negative health effects; instead, focus on including a variety of different fats in their diets in the appropriate amounts.

Saturated and unsaturated fats are both essential parts of our diet, but we should aim to include more unsaturated fats than saturated. Unsaturated fats (mono- and polyunsaturated) come primarily from plant foods, including oils (olive, canola, sesame), avocados, olives and nut butters, whereas saturated fats come from primarily animal products, including meats and dairy. Choose fish, lean cuts of meat and low-fat dairy when possible, but watch the added sugar that may be in products like yogurt. Finally, avoid trans fats at all costs! These fats are found primarily in margarines and processed baked goods, so take time to read food labels and look for zero grams trans fat.


Myth #4: the more protein you eat, the more weight you’ll lose

Overloading on protein won’t help you with weight loss, despite the promises made by many bodybuilding and fitness websites. Yes, protein recommendations change for different populations, as do the recommendations for all macronutrients. However, most healthy individuals (even athletes who need higher amounts of protein) rarely need a protein supplement to meet protein needs.

The key is to make sure the amount and timing are right for the protein you’re eating. Our bodies can absorb only a certain amount of protein at a time, so slamming down a protein shake packed with 60 grams of protein is not only a waste of money, but a waste of calories. Recent research shows that protein synthesis (building muscles) is more efficient when protein intake is consistent throughout the day. The typical American diet includes a low-protein breakfast (five to 10 grams), a moderate protein lunch (20 to 30 grams) and a high-protein dinner (60 to 80 grams). For optimal protein synthesis, breakfast, lunch and dinner should contain around 30 to 40 grams of protein. This may be a little higher or a little lower depending on each individual. Intake above 40 to 50 grams of protein at a meal does not seem to show any additional benefit for protein synthesis, meaning we can’t really do anything with all that extra protein.

Simply put, most people will get more benefit out of 90 grams of protein if they eat 30 grams at each meal. The more lean muscle mass you have, the more efficiently your body will be at burning calories. The more efficiently you burn calories, the easier it is to manage your weight.

Nutrition is not one size fits all, but using scientific facts to deconstruct some accepted diet myths can help you reach your goals.

So now you might ask, “Well, then how do I lose weight?” These major points can help you reach your goals and maintain them for life.

Possibly the most important recommendation I can give is to enjoy food! Food is an important part of most cultures and often the feature of many social events. What fun is it if you can’t enjoy the delicious pecan pie at the holiday party? The key to healthy eating for life is to enjoy the foods you love in appropriate portions. Pay attention while you eat; take the time to really taste your food and assess your hunger levels throughout each meal. As you become more in tune with your hunger, you’ll be able to honor that without guilt and stop when you’re full.


Our expert providers at Des Moines University Clinic can help you develop a nutrition, health and wellness plan tailored to your needs and goals. Visit the DMU Clinic website or call 515-271-1700 to schedule your appointment.

Disclaimer: This content is created for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified health care provider with any questions you may have regarding a medical condition.

Scroll to Top