Considering Keto?

ketogenic-dietThe claim

Ketogenic diets are the best way to lose weight and improve health

The ketogenic diet has been around for decades, but was popularized by Dr. Atkins in the late 1990s. Recently, it has become all the rage again.

Initial Google Search

What is the ketogenic diet?

It’s a low carb, moderate protein, high fat diet that helps your body use fat for fuel instead of sugar. People practicing a ketogenic diet usually eat about 75% fat, 20% protein, and only 5% carbs. Meanwhile, a typical American diet consists of around 35% fat, 15% protein, and 50% carbs.

Five percent is equal to 20-50 grams of carbs per day depending on your size. In food terms, one banana can contain more than your quota of carbs for an entire day.

What foods do people eat on a ketogenic diet?

You can eat any type of meat, fish, eggs, cheese, butter, non-starchy vegetables, leafy greens, avocados, nuts, seeds, and some berries. You can’t eat any sort of grains, legumes, sugars, most fruits, or starchy vegetables.

What happens inside your body when you drastically reduce carbohydrates?

Your body learns to rely on fat for energy. This is referred to as “ketosis”. When there are no carbs in your bloodstream, your insulin drops. The drop in insulin allows fat cells to be released into the blood stream. Then your body breaks down fat cells in the liver and turns them into ketones for your cells to run on instead of glucose.

If you read my last blog on fasting, you know that experts don’t completely agree on when the body is burning fat, sugar, or even muscle. But, the intermittent fasting and ketosis camp swears that the body doesn’t start burning fat until you’re in ketosis which can mean up to a week of almost no carbs.

How do you know when you’re in ketosis?

Some people use a blood glucose monitor (more accurate) or urine test strips (less accurate). Other signs include increased urination, dry mouth, bad/sweet breath, reduced hunger, and increased energy (after about a week).

Here is what proponents say:

  1. Ketogenic diets help you lose body fat by making your body use fat instead of sugar for fuel and by keeping you from feeling hungry.
  2. You will improve your heart health by increasing HDL (good cholesterol) and decreasing LDL (bad cholesterol), triglycerides, and blood pressure. It may also increase the size of your LDL, which makes the particles less dangerous.
  3. Your brain will function better. Not only will you be able to think more clearly and feel more alert, but you may also decrease your risk for developing Parkinson’s and Alzheimer’s disease.
  4. You will reduce your risk for developing cancer. The ketogenic diet will cause oxidative stress in cancer cells and it will reduce cancers associated with blood sugar or insulin problems.
  5. You’ll have clearer skin. Some forms of acne are thought to be related to blood sugar.
  6. It reduces seizures in children with epilepsy.
  7. It improves fertility in women with polycystic ovarian syndrome (PCOS)
  8. It can help people with type 2 diabetes manage their blood sugar and insulin levels, and maybe even stop needing medication.
  9. Your energy levels will improve.

However, many doctors and experts state the following in regards to keto:

  1. You lose muscle
  2. You become extremely fatigued
  3. You will enter “starvation mode” and stop losing weight
  4. You mostly lose water weight on keto
  5. It may slightly hinder athletic performance
  6. It’s hard to stick to because it eliminates so many foods
  7. It can cause damage to the heart
  8. If you have underlying kidney or liver problems, keto will make them worse
  9. You’ll be more likely to die prematurely from heart disease, stroke or cancer

Follow-up Questions

  1. Calories being equal, do people lose more fat on keto or non-keto diets?
  2. How do results hold up long term?
  3. Which claims are true? Which ones are hype or biased?
  4. I’ve read people who eat the fewest carbs are more likely to die prematurely. Are there confounding factors? Maybe people on keto were already more overweight or more at-risk.

Peer Reviewed Research

Inclusion criteria: Human clinical trials or meta-analyses of studies that compare a ketogenic diet to a traditional low calorie diet with the purpose of improving markers of metabolic syndrome. I did not include studies on healthy-weight people, athletes, or people with cancer, dementia, PCOS, or other special populations. The ketogenic diet is generally accepted by the medical community as effective for controlling epilepsy and slowing the growth of some types of cancer.

  1. Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. (2013)

This is a review of 13 randomized controlled trials, which compared a ketogenic group to a low-fat calorie restricted group. After a 1 year follow up, the people in the ketogenic group achieved greater weight loss and lower blood pressure than the low-fat group.

2. Long term successful weight loss with a combination biphasic ketogenic Mediterranean diet and Mediterranean diet maintenance protocol. (2013)

This study included 89 overweight subjects. They cycled between a 20-day ketogenic diet and longer maintenance periods of the Mediterranean diet for a year. The subjects lost and kept off 22 pounds on average. All markers of metabolic syndrome improved and all but 8 subjects were able to comply with the diet.

3. Metabolic impact of a ketogenic diet compared to a hypocaloric diet in obese children and adolescents. (2012)

This study compared 58 overweight children and adolescents. Half were assigned to a ketogenic group and half to a traditional calorie restricted group. The study lasted 6 months. In the end, all participants improved health markers and lost weight. The ketogenic group had better improvements than the calorie restricted group.

4. Comparison of a very low-calorie-ketogenic diet with a standard low-calorie diet in the treatment of obesity. (2014)

This study compared a ketogenic diet group with a reduced-calorie diet group. After 2 months, the ketogenic group lost an average of 29 pounds while the reduced calorie diet lost about 11 pounds. After a year, the group that had participated in the ketogenic group had lost an average of 44 pounds and the reduced calorie group only lost about 15. The ketogenic group preserved lean muscle mass and did not have any lasting side effects. This data was not reported for the other group.

5. Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. (2012)

This study included 363 overweight people. 102 of them had type 2 diabetes. Subjects were allowed to choose whether they wanted to be in the keto group or the low-calorie group. Results were measured after 24 weeks. Both diets improved markers of metabolic syndrome, but the keto group had more significant results. Many diabetics were able to decrease or discontinue their medication.

6. Short-term safety, tolerability and efficacy of a very low-calorie-ketogenic diet interventional weight loss program versus hypocaloric diet in patients with type 2 diabetes mellitus. (2016)

This study divided 89 overweight men and women into a keto group and a low-calorie group. After 4 months, results were measured. They found that the ketogenic diet was more effective in reducing body weight and improving glucose than the low calorie diet. It was also tolerated well by participants with diabetes.

7. A randomized trial of a low-carbohydrate diet vs orlistat plus a low-fat diet for weight loss. (2010)

This study included 146 overweight men who were divided into a keto group and a low-calorie plus orlistat (weight loss pill) diet. Subjects followed the diets for 48 weeks. Both groups had similar improvements in weight loss and blood glucose. The ketogenic diet was more effective for lowering blood pressure.

What We Know and Don’t Know

The research I found shows that the ketogenic diet is safe and effective for weight loss. In every study I found, it was more effective than a normal low-calorie diet. People on a ketogenic diet were able to improve all aspects of metabolic syndrome. No adverse health effects were reported in any human studies. These studies were robust, well-controlled, and measured effects after a reasonable amount of time (4-12 months).

In my analysis, I only included research comparing the ketogenic diet to another more traditional diet in overweight humans. However, I did read some studies on mice, athletes, cancer patients, etc. In general, the diet was safe and effective for all groups. Athletes tended to have improved cardiovascular performance without losing strength or muscle mass. Research on cancer and neurodegenerative disorders was in the preliminary phase. Many ideas and hypotheses were presented, but I found few clinical trials. However, the diet seems promising for at least some people with these conditions. Studies also found that keto improved symptoms of PCOS in some patients.

The research also confirmed that participants feel less hungry on the ketogenic diet than on traditional diets and that most participants were able to adhere to the diet.

Research in mice, however, did present some concerns. First, the diet seemed to cause problems with normal fertility, pregnancy, and lactation. Second, it caused biotin deficiency which can cause rashes, hair loss, depression, and other problems. However, this can be avoided by taking B vitamin supplements. Third, the ketogenic diet seemed to cause non-alcoholic fatty liver disease. These problems were not confirmed in human trials and may or may not be applicable.

Conclusions and Applications

Research supporting the ketogenic diet for weight loss is overwhelmingly positive. I would say that even though I personally felt like crap when I tried to go keto (I don’t think I ever got my carbs quite low enough), it’s definitely worth a try for most people with weight loss goals. I particularly like the idea of cycling keto with a low-calorie Mediterranean diet. For me, that sounds sustainable and may be a good way to avoid the potential for vitamin deficiency. It will be interesting to learn more about how doctors implement keto for treatment of conditions like cancer and Alzheimer’s in the future.


Author: Tara

Skeptical health and fitness enthusiast (and also speech-language pathologist)

One thought on “Considering Keto?”

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