Ketogenic diets are controversial popular diets that can temporarily help you to lose weight by restricting carbohydrates. A keto diet usually restricts carbohydrates that are absorbed only as sugars, and lets you eat lots of fat and moderate amounts of protein. You can’t eat a lot of protein because your body can convert protein into sugar, so a keto diet is essentially a high-fat diet. It restricts harmful sugared drinks and sugar-added foods, processed foods, and other refined carbohydrates usually found in bakery products, pastas and most dry breakfast cereals. These foods are associated with weight gain, diabetes and heart attacks (Nutrients, 2017 May; 9(5): 517).
You store significant amounts of sugar only in your muscles and liver. After a day of restricting carbohydrates, you use up your stored sugar and start to get most of your energy from fat, and when you use fat for energy, your body produces large amounts of ketones and uses them also for energy (Clin. Invest, 1967;46:1589–1595). However, the diet is complicated to follow and has many potential side effects.
Potential Problems with Keto Diets
Following a keto diet can both help and worsen various heart attack risk factors, and can improve some factors in type II diabetes. Keto diets have been associated with reduced heart attack risk factors. They can lower total and LDL cholesterol and triglycerides and increase HDL cholesterol (Nutr. Metab, 2008;5:36), and help to control blood sugar and reduce doses of the medications used to treat type II diabetics. However, keto diets:
- have not been shown to help keep that weight off long term after you have lost it
- are difficult for most people to stay on because of the limited choice of foods
- often restrict many healthful foods, such as fruits, beans, whole grains, and vegetables, that have repeatedly been shown to be associated with reduction of disease and extended life span
- usually encourage eating red meat and processed meats that have been associated with increased risk for heart attacks and premature death
- allow increased intake of saturated fats that may raise blood levels of the harmful LDL cholesterol, which is associated with increased risk for heart attacks
- restrict vegetarians who want to follow a keto diet to very limited sources of fats such as avocados, nuts or coconut oils
- in some studies, have caused rats and humans to develop diabetes by causing a fatty liver and insulin resistance (J. Clin. Endocrinol. Metab, 2005;90:2804–2809)
- can impair growth in children and cause kidney stones, osteoporosis and high cholesterol (Biomed. J, 2013;36:2).
Many people start to feel sick three to seven days after they start a keto diet, and symptoms usually last for a week to a month (“keto flu”). When their metabolism shifts from using primarily carbohydrates to fats, they may feel tired, not be able to think clearly, be hungry all the time, have difficulty falling asleep at night, and suffer nausea, constipation or diarrhea.
A Keto Diet Can Help to Prevent Seizures
The keto diet was originally developed in the 1920s to help control seizures. Your brain causes your muscles to contract by sending electrical messages along nerves to your muscles, and excessive transmission of electrical impulses along nerves causes seizures. The keto diet causes the brain to switch from its primary fuel, sugar, to ketones that are produced by your body when it uses fat for energy. Ketones help to prevent seizures by markedly increasing the passage of potassium through potassium ion channels to reduce the number and force of electrical signals sent from your brain to your muscles (Neuron, May 24, 2012).
I do not recommend ketogenic diets because they usually involve restricting unrefined carbohydrates. There is a huge difference between refined and unrefined carbohydrates. Unrefined carbohydrates as they are found in nature (in vegetables, fruits, beans, WHOLE grains, nuts and other seeds) are sources of healthful fiber and are associated with reduced risk for disease and increased life span. On the other hand, refined carbohydrates are a major cause of obesity, and diabetes, which increase risk for premature death. Also, many people on keto diets eat very large amounts of red meat and processed meats that are associated with increased risk for diseases and premature death.
If you want to prevent disease and prolong your life, I recommend that you:
- increase your intake of unrefined carbohydrates and decrease intake of refined carbohydrates: sugar-added foods, all sugared drinks including fruit juices, foods made from flour (bakery products, pastas, most dry breakfast cereals) and many other types of processed foods.
- get most of your protein from beans, nuts and other seeds, and restrict processed meats and meat from mammals. It is still controversial whether other foods from animals (dairy, eggs, poultry, seafood) are healthful or harmful.
- try to exercise every day
- avoid being overweight. If you want to lose weight, I recommend intermittent fasting
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe's full bio.