Keto Diet: Research Contradicts One Another

In recent years, the keto diet has been promoted as a miracle for people trying to lose weight. Unlike other advertised low-carb diets, which focus on higher protein intake, a ketogenic one shifts attention to fats.

The keto diet was first created to help treat epilepsy that did not respond to medication. Later, it became popular for reversing metabolic syndrome and improving insulin sensitivity. But a recent study suggests it might not help with these issues at all.

This article explains what the keto diet is, its possible benefits, and why new research hints its side effects might outweigh them.

What is the keto diet?

The goal of the keto diet is to shift your body’s primary energy source. Instead of glucose from carbohydrates, the diet relies on ketone bodies, a fuel the liver produces from stored fat.

However, getting the liver to produce ketone bodies is tricky, as you have to limit carbohydrates to 20–50 g per day. If it looks like a relatively high number, keep in mind that one cup of cooked white rice contains around 45 g of carbs.

Also, accidentally consuming too much protein may be harmful too. It slows the conversion of amino acids into glucose, which may raise blood sugar levels. To avoid this, it is recommended to consume about 75 g of protein per day on a 2,000-calorie diet. However, the exact number of nutrients depends on your specific needs.

Foods to focus on

To lower carbohydrate intake, the ketogenic diet suggests cutting down on:

1. Sweet fruits (grapes, bananas, oranges)
2. Grains (bread, pasta, rice)
3. Sugar (soda, candies, desserts)

In exchange, it suggests focusing on these foods:

1. Healthy fats (avocados, olive oil, seeds, butter)
2. Nuts (almonds, macadamia, walnuts)
3. Full-fat dairy (cheese, milk, Greek yogurt)
4. Fatty meats (fish, pork, bacon, chicken)
5. Low-carb vegetables (broccoli, onions, bell peppers, asparagus)
6. Drinks without sugar

Potential benefits of the keto diet

People who promote the keto diet on social media often mention its health benefits, and some studies support those claims.

Lower blood sugar levels

In its guidelines, the American Diabetes Association suggests that people with diabetes should consider low-carbohydrate or Mediterranean diets in order to control sugar levels in their blood.

A recent Stanford trial compared the two diets to see which has more benefits. In the study, half of the 40 participants started with the ketogenic diet, and the other half with the Mediterranean diet. After 12 weeks, the groups switched.

The researchers found that both diets were associated with blood glucose control improvement, with sugar dropping by 9% on the keto diet and 7% on the Mediterranean diet. Weight loss was relatively similar too: 8% on keto and 7% on the Mediterranean.

Even though these numbers are promising, there is one problem. Maintaining a ketogenic diet may be difficult because it eliminates legumes, most fruits, and grains.

Weight loss

The exact reason why a ketogenic diet leads to weight loss is still debated. However, a 2024 study tried to find that answer.

First, the researchers studied healthy people with a normal weight and saw good results. Then, they tested the diet on people who weighed more. After three months, these participants lost significant weight, mostly from body fat, while their muscle and bone mass remained unchanged.

This result prompted researchers to investigate why it happened. One theory suggests that people who lost weight may have benefited from better-quality food, since the keto diet often limits processed foods and focuses on whole, unprocessed foods.

Another theory looked at how carbs affect the body. Foods high in carbs can cause insulin spikes, which may lead to more fat storage. Eating fewer carbs may help the body use energy better. Instead of just cutting calories, researchers changed the balance of nutrients. They found that weight loss depended on more than just eating less, as shown by the drop in long-term blood sugar in the study.

Mental health support

People who take medication for mental illnesses like schizophrenia or bipolar disorder may have side effects such as insulin resistance or weight gain. For some, these side effects may even lead them to stop taking their medication.

In order to help these people, Stanford Medicine conducted a pilot study to see how the ketogenic diet affected people with these mental illnesses. Even though it’s a small research, its results show potential for further investigations.

After four months, participants lost an average of 12% of their body weight and reduced their waist size by 11%. Researchers also observed that they had lower blood pressure, body mass index, triglycerides, blood sugar, and insulin resistance.

The benefits for mental health were also noticeable. Participants reported enhanced sleep and mood, and demonstrated a 31% improvement on the Clinical Global Impression Scale. This tool is used by doctors as a quick, clear way to understand a patient’s overall mental health before and after treatment.

A new point of view on the keto diet

A recent study by University of Utah Health researchers used mice to examine the long-term metabolic effects of the keto diet. Unlike most trials, which were short-term, this trial lasted nearly a year, providing greater insight into the long-term effects of high-fat diets.

While animal studies do not always directly translate to humans, this research highlights potential risks to metabolic health and liver function.

Glucose intolerance

In contrast to studies supporting the keto diet for individuals with diabetes, this research found that mice developed severe glucose intolerance, which worsened over time.

Importantly, this glucose intolerance was not due to insulin resistance. Mice on the keto diet stayed sensitive to it and did not release enough insulin when needed. This suggests that long-term high-fat intake may stress pancreatic cells and impair their function.

There is some good news, though, as these effects may be reversible the minute you stop the ketogenic diet.

Fatty liver

Because the keto diet is so high in fat, researchers examined how it affects blood and liver fat levels. They found that mice on the keto diet had much higher blood fat than mice on other diets.

These high blood fat levels were linked to liver problems, especially in male mice. After a long time on the keto diet, male mice developed fatty liver, inflammation, and poor liver function. Female mice, however, were mostly unaffected by these changes. The researchers plan to study why this happens.

Bottom line: what to trust?

If you are considering the keto diet and are uncertain due to conflicting research, it is important to base your decision on your individual health goals and needs. While the keto diet may benefit certain conditions, such as epilepsy and diabetes, it is essential to determine what is most appropriate for you. Consulting a healthcare professional is recommended, as the keto diet may have side effects.