Do Low Carb Diets Work? Understanding the Low Carb Diet

By Jocelin Boucher RDN, LDN. This article was originally published on DayByDayNutrition.org and has been republished here with permission from the author.

The low carb craze is here and has been a hot topic of debate for many years. But do low carb diets work? Are they worth it?

We're going to look at those questions, the history of the low carb diet, and if they're worth it in this post. Let's get started!

A Staple in American Culture

In a way, this diet and many like it are ingrained in American culture. For this reason, I want to dedicate a little time to really dive into why a very low carbohydrate diet is considered a fad diet in the first place, why people practice and try them, and ultimately decide if this diet is something to try.

First, making a decision to practice a certain diet should include education. You're already on the right track by asking "do low carb diets work" and the other questions we addressed earlier.

It is important to know the research that has been done on short term and long term effects of practicing a certain diet so that you can trust outcomes from the food choices you make. 

You want to make sure it works and is safe; whether you are looking for weight loss, blood sugar control, blood pressure control, etc. A fad diet typically either leaves some science out of the full picture or lacks bigger picture and long term outcomes, making it unsustainable and not a lifestyle.

A Fad Diet

The low carbohydrate fad diet has been around for generations. It has a lot of promise and creates quick results. 

However, there is a reason why low carb/no carb is considered a fad diet and not a realistic lifestyle. A fad low carb/no carb diet would be considered no fruit, no starchy vegetables (potato, corn, peas, legumes), no grains, no sugar, no wheat, etc. 

It eliminates foods that would turn into glucose in the blood after eating and digesting. The Keto and Atkins diets both follow these guidelines.

When you eat carbohydrates, your body will use them for fuel and blood sugar regulation. 

Carbohydrates not used immediately do not get stored as fat. Rather, they are stored in the liver as glycogen. Conversely, dietary fat, protein, and alcohol do get stored as fat. 

The liver is a reserve that holds glycogen. When needed, the glycogen will get reverted back to glucose to keep blood sugar levels stable and feed your brain. This is evident when you are sleeping or not eating for long periods of time.

Facts About Glycogen

A unique fact about glycogen and being stored in the liver is that it also carries water. On a very low carbohydrate diet, glycogen levels in the liver will be depleted. 

When this happens, excess water is also lost resulting in weight loss. People can lose 5-10 pounds of water weight in a week during this process. 

Doing this for a week or two is not going to cause harm for normal healthy adults as the body will adapt to not having carbohydrates to run on by burning fatty acids. But asking do low carb diets work in the long term provides an entirely different answer.

The fatty acids will turn into ketones which is where the Keto diet gets its name. Your brain can run on ketones but it is not as efficient and you might feel less alert and a bit foggy. 

If you are burning fatty acids instead of carbohydrates for energy, then that will lead to weight loss too, not just water loss, right? There is merit to this argument. However, if you are cutting out carbs, you are inherently eating a lot more fat and protein to feel satisfied. This is because you're going to lack the fiber from fruit, vegetables, and whole grains (things that low carb dieters do not eat). 

Packing in Calorific Foods to Feel Full

Fat is incredibly dense in calories. Calories are important to recognize here because calories are the foundation that drive weight loss (usually what low carb dieters look for as outcomes). 

Fat is nine Calories per gram where protein and carbohydrates are four calories per gram. This means that one tablespoon of olive oil is 120 calories and one tablespoon of rice cooked is 13 calories. 

This is a staggering difference. Knowing this, the water loss being driver of weight loss makes more sense since you probably are not cutting many calories. BUT, if you are under calories doing low carb, you probably are eating protein as your main energy source leading to risks of its own that we will discuss.

Increased Saturated Fats

Another effect of high fat and low carb is the risk of increased saturated fat intake. Animal meat is a dense source of saturated fat and you are more likely to eat more animal meat if eliminating most carbohydrates. 

Saturated fat is known to be correlated with heart disease and it is recommended that no more than 10% of total calories come from saturated fat (animal, dairy, coconut oil, palm oil). 

For reference, that is about 15 grams of saturated fat in a day where 1500 calories is the average intake. Traditionally, in the American food system (unless buying USDA organic) many animals are treated with high amounts of hormones and antibiotics, found primarily in the fat. 

By following a diet high in traditional American food system meat, you are exposing yourself to more of those substances. Research shows that long term exposure to these hormones and antibiotics can lead to antibiotic resistance and various cancers.

Do Low Carb Diets Work in the Long Term? Not Really

Low carb diets inherently create a high fat and protein diet. Protein is not an optimal energy source and should only account for 20% of your total calorie intake or .8 grams per kg of body weight. Protein is primarily used for building blocks in the body to make tissue and other things. 

An additional danger with diets like Keto and Atkins have a lot to do with eating too much protein. If you eat more than you need, your kidneys have to process extra protein for energy or break it down to be stored as fat. 

Because kidneys are extremely fragile, eating too much protein over an extended period of time can damage the tubules that filter your blood, resulting in kidney failure. If both kidneys are failing, a transplant or dialysis will be required, which is something to be avoided.

The truth is, in short term, the answer to "do low carb diets work?" is yes: a very low carbohydrate diet can help shed a few pounds quickly without harm if you’re a generally healthy adult. 

However, there are many more dangers in the long term and there are more sustainable ways to lose weight and maintain a healthy lifestyle. 

In a pinch, a low carb diet can be a good catalyst in changing eating habits to start going in the right direction. After all, it gives a fast result of weight loss (positive feedback) and it helps you cut out a lot of unhealthy foods. Some very carb heavy foods that are good to avoid are: 

• Cookies
• Cake
• White pasta
• White rice
• White bread
• Candy
• Fruit juice
• Soda
• Chips
• Pretzels

Avoiding these is good because they do not provide any vitamins or minerals integral to a healthy metabolism and gene expression. They also lack the fiber that keeps you full and helps maintain blood sugar. 

When the body absorbs refined carbs such as a big bowl of white pasta or full glass of fruit juice, your blood sugar will spike and your body will store it as quickly as possible to regulate it. This can make you feel tired and irritable soon after eating, developing a craving for more carbs leading to overeating calories and resulting in weight gain. I call this the carb coaster.

The Best Solution

What’s the best solution? Work to limit or eliminate refined carbohydrates and replace them with complex carbohydrates full of important vitamins and minerals, keeping your body in optimal condition including weight loss. 

Complex carbs are: Beans, legumes, fruit, vegetables (yes all! Eat the skin of your potato for fiber and don’t load it with butter to keep calories down). Keep the denser carbs such as whole grains, whole wheat pasta/bread to smaller portions to prevent riding the carb coaster but still should be eaten for nutritional benefits. 

When working on weight loss, you want to only lose about 1-2 pounds per week with nutrition changes and exercise, otherwise it is not realistic and probably is water weight or muscle loss! 

Just remember, take it Day By Day!

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