The ketogenic diet, often called the "keto" diet, has exploded in popularity as a weight-loss strategy. Though it may seem newer to your newsfeed, the ketogenic diet has been around since the 1920s. The keto diet is all about cutting carbs and eating more fat, similar to the Atkins diet from the 1970s. The premise of the ketogenic diet for weight loss is that if you deprive the body of glucose-the main source of energy for all cells in the body, which is obtained by eating carbohydrate foods-an alternative fuel called ketones is produced from stored fat (thus, the term “keto”-genic).
What is the Keto Diet?
The keto diet reduces your total carb intake to less than 50 grams a day. This is the equivalent of a cup of white rice. The keto diet excludes carb-rich foods like grains, beans, fruits and starchy vegetables. The ketogenic diet typically reduces total carbohydrate intake to less than 50 grams a day-less than the amount found in a medium plain bagel-and can be as low as 20 grams a day. Generally, popular ketogenic resources suggest an average of 70-80% fat from total daily calories, 5-10% carbohydrate, and 10-20% protein. For a 2000-calorie diet, this translates to about 165 grams fat, 40 grams carbohydrate, and 75 grams protein. The protein amount on the ketogenic diet is kept moderate in comparison with other low-carb high-protein diets, because eating too much protein can prevent ketosis.
Roshini G. Merneedi, RD, a dietitian at Northwestern Medicine, explains that your body's primary energy source is glucose, which comes from the breakdown of carbohydrates. The keto diet limits carbohydrates, forcing your body to burn fat for fuel instead. When these stores are full, they are converted into fat. In this state, your body breaks down fats into molecules called ketones. Ketones serve as an alternative fuel source.
Ketosis Explained
During fasting, or when very little carbohydrate is eaten, the body first pulls stored glucose from the liver and temporarily breaks down muscle to release glucose. If this continues for 3-4 days and stored glucose is fully depleted, blood levels of a hormone called insulin decrease, and the body begins to use fat as its primary fuel. The liver produces ketone bodies from fat, which can be used in the absence of glucose. When ketone bodies accumulate in the blood, this is called ketosis. Healthy individuals naturally experience mild ketosis during periods of fasting (e.g., sleeping overnight) and very strenuous exercise.
Ketoacidosis vs. Ketosis
Excessive ketone bodies can produce a dangerously toxic level of acid in the blood, called ketoacidosis. During ketoacidosis, the kidneys begin to excrete ketone bodies along with body water in the urine, causing some fluid-related weight loss. Ketoacidosis most often occurs in individuals with type 1 diabetes because they do not produce insulin, a hormone that prevents the overproduction of ketones. However in a few rare cases, ketoacidosis has been reported to occur in nondiabetic individuals following a prolonged very low carbohydrate diet.
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Potential Benefits of the Keto Diet
“There has been anecdotal evidence of people losing weight on the ketogenic diet. People also report feeling less hungry than on other types of restricted diets,” says Melinda R. Ring, MD, director of Northwestern Medicine Osher Center for Integrative Health. On paper, burning fats by eating more of them is enticing, which is why the keto diet has become popular. The keto diet allows many people to eat the types of high-fat foods that they enjoy, such as red meats, fatty fish, nuts, cheese and butter, while still losing weight.
There is evidence that the keto diet can help specific groups of people. The keto diet helps reduce seizures in children with epilepsy. Endurance athletes and body builders also use it to scrap fat in short timeframes. The keto diet is being studied for reducing symptoms for patients with progressive neurological disorders like Parkinson’s disease. But scientific research has not confirmed benefits for these patients, Dr. Ring says, and more research is needed before it can be widely recommended.
KD has been shown to effectively lead to weight loss, reduction in hyperinsulinemia, and improvement in insulin sensitivity.
Along with weight loss, health parameters associated with carrying excess weight have improved, such as insulin resistance, high blood pressure, and elevated cholesterol and triglycerides.
The keto diet - a high-fat diet that keeps your body in a state of ketosis - has its perks. It can help your metabolism speed up, increase your muscle mass and improve your blood pressure - all while helping you lose fat.
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Keto and PCOS
KD has been postulated to positively impact women diagnosed with polycystic ovarian syndrome (PCOS). Women with PCOS experience symptoms of irregular/absent menses, infertility, obesity, and other phenotypical effects of hyperandrogenism such as hirsutism. PCOS is closely associated with other metabolic and endocrinological irregularities, which include insulin resistance, hyperinsulinemia, type 2 diabetes mellitus, dyslipidemia, and hyperandrogenism [12]. PCOS is accompanied by key features such as insulin resistance, androgen excess, and abnormal gonadotropin dynamics. In turn, treatment is targeted towards improving insulin resistance, weight loss, decreasing luteinizing hormone (LH) and follicular stimulating hormone (FSH) ratios, and excess androgens. A study by Mavropoulos et al. implemented KD for women between the ages of 18-45 years diagnosed with PCOS, with a BMI greater than 27 kg/m2, and no other serious medical conditions. Participants adhered to a six-month period of strict KD consisting of less than 20 g of CHO per day with unlimited consumption of animal-based foods. After 24 weeks, the results of the study (pre- and post-design) showed a statistically significant decrease in fasting serum insulin (23.5 to 8.2, p=0.002), LH-to-FSH ratio (2.23 to 1.21, p≤0.05), and free testosterone (2.19 to 1.70, p≤0.05). Furthermore, the study subjects had an overall mean body weight change from baseline of -12.1% and a mean decrease in BMI of 4.0 kg/m2 (p=0.0006) [12].
Keto for Diabetics
Management of type 1 and type 2 diabetes generally consists of medication adjustments targeted toward glycemic control and an HbA1c level of <7%. As mentioned previously with regard to patients with PCOS, the same benefits of following a VLCKD apply to patients with diabetes as well. In an outpatient clinic study by Yancy et al., overweight patients diagnosed with type 2 diabetes were made to follow a VLCKD throughout 16 weeks with the primary outcome measure of monitoring blood glucose control through HbA1c levels. The 28 participants enrolled were restricted to less than 20 g of CHO per day. At the end of the 16-week timeframe, HbA1c decreased from 7.5 ±1.4% to 6.3 ±1.0% (p<0.001). The absolute decrease in HgA1c was approximately 1.0% in 11 participants (52%). The relative decrease in HgA1c from baseline was >10% in 14 participants, and >20% in six participants.
Risks and Side Effects
Because of the stringent food restrictions, many find the keto diet hard to stick to. “The ketogenic diet can be effective for weight loss when used in a short time period followed by the adoption of healthier eating habits,” says Baljash Singh Cheema, MD, a cardiologist at Northwestern Medicine Bluhm Cardiovascular Institute. “However, we know in studies of these types of diets that once people stop following that diet, they regain at least half of the weight that they lost. Ketosis is difficult to achieve because it’s like a light switch: either on or off. Individuals who consistently track food intake are more likely to remain in ketosis.
“Because the keto diet is so restricted, you’re not receiving the nutrients - vitamins, minerals, fibers - that you get from fresh fruits, legumes, vegetables and whole grains,” says Dr. Ring. People report feeling foggy, irritable, nauseous and tired. “In particular, low fiber intake can disrupt gut microbiota and lead to chronic constipation, while inadequate magnesium, vitamin C and potassium can contribute to muscle cramps, fatigue and weakened immune function,” explains Dr.
The high-fat nature of the diet could also have negative impacts on heart health. The American Heart Association recommends limiting saturated fat intake to less than 6%. “In practice, many people eat high amounts of saturated fats, which could increase your risk of heart disease,” says Dr. Cheema. “You may be eating a lot of fatty meat thinking it’s a good thing for you because it's high in fat. This can dramatically alter your lipid profile. While high-fat diets can elevate LDL (“bad”) cholesterol, the type of saturated fat matters. The bottom line is that having more fats in your diet can lead to higher cholesterol. “We know that higher cholesterol tends to increase your chances of heart attacks and strokes,” says Dr. Cheema.
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The keto diet may not be appropriate for everyone, specifically people with kidney disease. “Although more research is needed in that area, there is some suggestion that it can make kidney disease worse over time,” says Dr. Some people also experience dehydration on the keto diet because they’re eliminating glycogen, which holds water, from the bloodstream.
When you micromanage your food intake by tracking how much you eat, it disconnects you from what your body is asking for. You start using outside numbers to determine what to eat instead of listening to your body. “Being intuitive and understanding what your body needs is essential for proper nourishment,” says Merneedi. Monitoring food so closely can lead to psychological distress, such as shame and binge eating.
The keto diet can cause your blood pressure to drop in the short term due to a reduction in blood volume and changes in your fluid balance. Symptoms of low blood pressure include dizziness, lightheadedness or fainting, especially when standing up quickly. Following a keto diet can also cause your blood sugar to drop, which can be dangerous for people living with diabetes. Common symptoms of low blood sugar include weakness or shaking, sweating, a fast heartbeat and dizziness.
Common short-term side effects resulting from the initiation of KD have been referred to as “keto flu,” which encompasses symptoms including fatigue, headache, dizziness, nausea, vomiting, constipation, and low exercise tolerance [6]. Symptoms typically resolve after a few days to weeks as the body adjusts to the low CHO, ketogenic state. Long-term side effects include hepatic steatosis, kidney stones, hypoproteinemia, and vitamin deficiency.
Some negative side effects of a long-term ketogenic diet have been suggested, including increased risk of kidney stones and osteoporosis, and increased blood levels of uric acid (a risk factor for gout). Possible nutrient deficiencies may arise if a variety of recommended foods on the ketogenic diet are not included.
The Importance of Food Quality
As reported by Seidelmann et al. in a prospective cohort study and meta-analysis, it is not only a matter of CHO restriction but also the quality of food ingested. The study’s primary outcome measure was all-cause mortality. After multivariable adjustment and a median follow-up period of 25 years, a U-shape association was observed between the percentage of energy consumed from CHO and mortality [pooled hazard ratio (HR): 1.20 (95% CI: 1.09 to 1.32 for low CHO consumption); pooled HR: 1.23 (95% CI: 1.11 to 1.36 for high CHO consumption)] in the Atherosclerosis Risk in Communities (ARIC) cohort. The authors emphasized that both low (<40%) and high CHO consumption (>70%) conferred higher mortality when compared with moderate CHO intake. Further analysis of the results demonstrated that mortality was worse when fat and protein sources were animal-derived instead of plant-derived.
Keto Supplements: Gummies, Oils, and Powders
Keeping your body in ketosis can be hard - doing so includes eating a restricted list of foods like meat, eggs, nuts and fish and avoiding foods like fruit, sugar, beans and high-carb veggies. And that’s why you’ve probably seen information on keto pills, keto oil and keto powders - as well as keto gummies. These different products claim they help keep your body in ketosis.
Keto gummies are made with exogenous ketones, which is a fancy term for ketones you get from an outside source. “Your body makes ketones on its own through the foods you eat,” explains registered dietitian Beth Czerwony, RD, LD. “Keto gummies are a supplement that adds exogenous ketones into your body, which may help continue ketosis.” It’s important to note that keto gummies (or any keto supplement, for that matter) don’t put you in ketosis. “Keto gummies may help the process of ketosis continue, but you need to be in ketosis first,” clarifies Czerwony.
Ingredients in Keto Gummies
Most keto gummies typically contain medium-chain triglycerides (MCTs), a type of saturated fat that help give your body energy, in addition to exogenous ketones. “Sometimes, keto gummies may contain gelatin or natural sweeteners like Stevia,” notes Czerwony. “It’s not like eating a traditional gummy. It’s not going to have any additional sugars because if it did, then it would throw you out of ketosis.”
Potential Benefits of Keto Gummies
There’s limited research on the benefits of keto gummies. Czerwony says potential benefits include:
- Increase weight loss.
- Improve athletic performance.
- Decrease your appetite.
But, again, whether keto gummies or other keto supplements can actually keep you in ketosis has been inconclusive, according to research. In fact, one study explains that supplements may increase the amount of ketones too much. Ideally, your body wants to maintain an even level of ketones. And when this happens, your liver may not produce as many ketones naturally, making it harder to stay in ketosis.
Potential Risks of Keto Gummies
Czerwony says those potential risks include:
- Nausea and vomiting.
- Gastrointestinal issues, like diarrhea.
- Low blood sugar.
“You run the risk of GI issues if your keto gummies use sorbitol, which is known as a laxative,” warns Czerwony. “You should be cautious if you’re going try it. Slowly introduce keto gummies to see how you do because you don’t want to all sudden just kind of overdo it and have those side effects and not be very happy.”
Alternatives to Keto
For long-term weight loss, Dr. Ring, Dr. Intermittent fasting is an approach that allows you to receive the benefits of ketosis while still eating a varied and balanced diet, says Dr. Ring. By cycling between periods of eating and fasting, your body enters “mild ketosis” during the fasting phase. “Unlike the keto diet, which requires strict food restrictions, intermittent fasting lets you enjoy a variety of nutrient-dense foods, such as fruits, vegetables, whole grains and legumes, during eating windows,” Dr. Ring explains.
Dr. Cheema advocates making small changes based on your health goals. “People tend to burn out on those big goals and challenges, and then they go back into their own habits,” he explains. “Just because you were super fit between the ages of 36 and 38 may not extend your healthy life. But if you make small changes consistently every day from ages 36 to 66, that probably will have a big impact.