Keto, short for a ketogenic diet, has been hugely popular over the past couple of years. I have many friends who follow a keto diet and even recommend it to their patients. But there have been some recent news articles warning about the dangers of keto. So what’s the truth? Is keto the best invention since sliced bread (which you wouldn’t eat on a keto diet anyway) or is it a fast-track to a shorter lifespan? Read on to find out.
What is keto?
Keto is more than a low carb diet. The definition of low carb depends on which study you’re looking at, but a general rule of thumb is any diet where <45% of your daily calories are from carbs. So if you eat 2000 calories per day, this is 225g of carbs. Anything lower than that is considered low carb.
For a keto diet, however, the goal is to put your body in ketosis (read below to find out what this means). This requires an extremely low amount of daily carbohydrates: usually less than 50-100g of carbs per day.
What is ketosis?
Fat is broken down ultimately into carbon dioxide and water. But this process takes just a little bit of glucose. When no glucose is present (i.e. from eating carbohydrates) fat is instead broken down into ketone bodies. These ketone bodies can be used directly as fuel by our bodies, and some spill out into the urine, which is why people will use urine testing strips to see if they are in ketosis.
Why does ketosis result in weight loss?
There are a couple theories explaining why ketosis results in weight loss.
- Ketosis wastes a little bit of energy. Basically the fat molecules aren’t quite broken down all the way when we use them as ketone bodies rather than metabolizing them all the way down to carbon dioxide and water. In addition, some ketone bodies are lost in the urine. This is the theory I learned in medical school, but I think it’s actually a small part of the picture.
- Hormones actually regulate our weight, namely insulin. Insulin is released in response to eating carbohydrates. And a small amount is released in response to eating protein. But no insulin is released in response to eating fat. The keto diet results in less insulin release, and therefore the body weight decreases. This theory explains why you can lose weight with low carb alone (i.e. not keto) and why intermittent fasting works, so I think it’s a more accurate picture of how our bodies control weight.
So are there dangers of keto?
A recent study in the Lancet found a higher risk for death for either very low or very high carb diets. This was a 25 year study looking at over 15,000, so they’ve got a lot of data to look at. The study found that people who took in 40-70% of calories from carbs had the lowest overall mortality. People who ate both very low carb and very high carb diets had a higher mortality rate.
Furthermore, the type of fats and proteins matter (since this is what makes up the rest of your non-carbohydrate diet). Plant fats and proteins were associated with a lower risk of death. One important point: plant proteins are usually a very small part of a ketogenic diet because they have carbohydrates as well. Keto diets tend to be very heavy in sources of animal protein and fat.
Keto has a few negatives
- it’s very hard to maintain. Keeping carb intake to <50 or 100g per day cuts out a lot of fruits and vegetables, and most sources of plant protein (legumes like beans, chickpeas, and lentils, and even some nuts).
- We don’t know the long-term effects. The study I mentioned above isn’t specific to keto- just low-carb diets in general. Keto is extremely low carb, and there aren’t any long-term studies of keto. In fact, there are very few studies looking at the ketogenic diet for weight loss. In the medical community the ketogenic diet is actually used in children with seizure disorders, but rarely for weight loss.
- It’s not really necessary. You can absolutely get to and maintain a healthy weight without doing low carb.
- It moves you away from a plant based diet. Plant-based diets have been shown to decrease the risk of diabetes, coronary artery disease, and hypertension.
- Ketogenic diets generally have less fiber. And fiber has numerous health benefits, including a possible decreased risk of colon cancer.
Should you try keto?
If you do, get your doctor’s okay first. And don’t plan to stay on it long-term, because it’s simply not sustainable for most people.
One big drawback of the keto diet? It doesn’t address why we eat, and that’s half the battle. Our emotions impact our weight pretty significantly. Don’t believe me? Take the quiz to see if your emotions affect your weight: