Are ketones the answer for weight loss? Many nutrition experts and followers of the keto diet say yes. But what are ketones, and how they can help you lose weight? The answer lies in your physiology.
When you follow a low carb or keto diet, your body has to find an alternate way to get energy instead of from its beloved glucose. It does this through a process called ketosis, which involves the creation of ketones, or energy-rich substances made from fatty acids. If you stick with it, the creation of ketones breaks down your fat stores, translating into weight loss over time.
The Energy Cycle
Carbohydrates are your body's main energy source. When you eat carbohydrate-rich foods, they move through your digestive system where they are broken down into their simplest form, a sugar called glucose. Glucose gets absorbed into your bloodstream where its presence tells your pancreas to release the hormone insulin.
Insulin attaches to glucose molecules and carries them to your cells. The cells take what they need for immediate energy and then convert some of the rest into a compound called glycogen. Insulin carries the glycogen to your liver, where it's stored for later. But your liver can only store so much glycogen.
Once the liver is full of glycogen stores, any leftover glucose is converted to a fat called triglycerides, which is stored in your adipose, or fatty, tissue. If you regularly eat carbohydrates, this cycle continues. However, if you interrupt the cycle by following a low carb or ketogenic diet, something interesting happens.
What Is Ketosis?
Since your body no longer has access to glucose, it turns somewhere else for energy. After you use up all of the glucose and stored glycogen in your liver, your body will start breaking down the fatty acids in your fat tissue.
It then turns these fatty acids into compounds called ketones, which your brain and the rest of your body can use for energy. The presence of ketones in your blood is called ketosis. To effectively push your body into making ketones, you have to avoid high-carbohydrate foods, like:
- Grains (refined and whole)
- Fruits (with the exception of occasional berries)
- Desserts and anything with added sugar
- Starchy vegetables (carrots, potatoes, sweet potatoes, peas)
- Beans and other legumes
- Soda and sweetened beverages
Ketones and Weight Loss
Because your body is using the fat from your fat stores to create ketone bodies, you may naturally lose weight when you go into ketosis; but the connection between ketones and weight loss doesn't end there. A report published in the International Journal of Environmental Research and Public Health in February 2014 found several other mechanisms by which ketones can help you lose weight.
According to researchers from the study, ketones help:
- Suppress appetite directly
- Suppress appetite by balancing the hunger hormones ghrelin and leptin
- Reduce the amount of fat your body stores, while simultaneously increasing the amount of fat your body burns
- Boost calorie burn, since it takes more energy to create ketones than it does to use glucose
The report further details how a ketogenic diet may also be connected to less yo-yo dieting and weight regain than its low-fat counterparts. In other words, you're more likely to keep off the weight you lose. Another study published in Obesity Science and Practice in January 2016 added that, when compared to low-fat diets, low-carb and keto diets result in greater weight loss and overall better body composition (or less body fat and more lean muscle mass).
Types of Ketones
Acetoacetate is created first and then converted into beta-hydroxybutyrate. These two ketone bodies are the ones that are in your blood in the highest concentrations. They supply your body with the energy you need in the absence of glucose. Acetone is created as a byproduct of the breakdown of acetoacetate. The concentration of acetone in the body is much lower than the other two.
Acetone is the ketone responsible for the fruity "keto breath" that many people report once they get into ketosis. With the rise in popularity of the keto diet, many supplement manufacturers were looking for a way to appeal to the masses. Thus supplemental ketones, also called exogenous ketones, were born. But do they have the same effect as the ketones your body makes naturally?
Effect of Ketone Supplements
Researchers from a study published in Obesity in February 2018 seem to think so. For the study, normal weight participants were given supplemental ketones in the form of a drink filled with beta-hydroxybutyrate. After 60 minutes, the exogenous ketones increased blood ketone levels from 0.2 to 3.3 millimoles.
Accompanying the rapid increase in ketones was also a measurable lowering of ghrelin, a hormone that stimulates appetite and promotes fat storage. In other words, when ghrelin goes down, you feel less hungry and you store less fat, two factors that can lead to weight loss. In addition to the results seen on the blood tests, participants in the study reported that they didn't feel hungry or have a desire to eat following the supplementation.
A report published in the Journal of Physiology in May 2017 adds that exogenous ketones may boost the metabolism of skeletal muscle during exercise, which can increase performance, especially in endurance and elite athletes. However, the study also notes that the data is preliminary and the effects are typically seen only in highly-trained athletes.
Ketosis Versus Ketoacidosis
When discussing ketosis, it's important to differentiate between nutritional ketosis and diabetic ketoacidosis, which is a potentially life-threatening condition that can occur in people with type 1 diabetes. In ketoacidosis, the body begins breaking down fat and producing ketones at a rapid rate that's too fast for the body to keep up with.
As a result, the ketones, specifically the beta-hydroxybutyrate ketone body, build up in the blood, causing the blood to become too acidic. This happens due to a combination of the body making too much glucose and its inability to effectively use the sugar. Some common symptoms of diabetic ketoacidosis include:
- Changes in alertness/fainting
- Rapid breathing
- Dry skin and mouth
- Flushed face
- Frequent urination
- Excess thirst
- Stomach pain
- Obesity: "A Ketone Ester Drink Lowers Human Ghrelin and Appetite"
- MedlinePlus: "Diabetic Ketoacidosis"
- Lab Tests Online: "Blood Ketones"
- Diapedia: "Ketone Body Metabolism"
- Obesity Science and Practice: "Adherence to Low‐Carbohydrate and Low‐Fat Diets in Relation to Weight Loss and Cardiovascular Risk Factors"
- The Journal of Physiology: "Metabolism of Ketone Bodies During Exercise and Training: Physiological Basis for Exogenous Supplementation"
- International Journal of Environmental Research and Public Health: "Ketogenic Diet for Obesity: Friend or Foe?"
- Harvard T.H. Chan School of Public Health: "Carbohydrates and Blood Sugar"
- National Council on Strength and Fitness: "Converting Carbohydrates to Triglycerides"