Kaitlyn Freels, National Center for Health Research
The keto diet is one of the fastest growing diet trends. Claims of success from celebrities and athletes like the Kardashians and Lebron James have led many to slash carbs. But is this carb-reducing diet healthy? Or is moderation the key to long-term success?
What is the Keto Diet?
The keto diet is a high-fat, low-carb diet. Carbohydrates (carbs) are the primary source of energy through our diet. Fifty grams per day is the maximum amount of carbs recommended on this diet. To put this in perspective, that’s about 3 slices of bread every day. Some keto meal plans suggest even less. So where is the energy we need coming from without carbs/on the keto diet?
When the body runs out of energy from carbs, it shifts to producing it from other, less efficient sources like protein and fat. After a few days, your metabolism shifts to a starvation state known as ketosis, as a result of the body breaking down fat. This state is the body’s natural energy backup plan in the event of extreme hunger or famine. The goal – supported by some studies – is to make your metabolism work less efficiently, causing relatively more weight loss than low-fat diets for the same amount of calories eaten.1 However, it is also a slower process of producing energy, which means there will be no bursts of energy after a meal or snack.
Cutting carbs is also the core principle of the Atkins Diet. The diet was first developed in the 1960s, revived in the early 2000’s, and has had fluctuating popularity since. Both diets limit carbs and have no calorie restriction. The keto diet restricts daily protein intake (20-25%) and emphasizes fat intake. The Atkins diet does not make this distinction between protein and fat. Additionally, the Atkins diet has several stages. Only the initial phase of Atkins restricts carbs to cause ketosis; after that, carbohydrate intake is slowly increased as weight loss milestones are passed. In contrast, the keto diet aims to consistently restrict carbs and cause ketosis.
Moreover, there are risks associated with the keto diet, and keeping the body in this state requires strict adherence to the diet. Even sneaking a few extra carbs is enough to disrupt the state of ketosis and cause the diet to be ineffective. In order for the diet to work, followers need to be very aware of what foods (proteins, fats, and carbs) they can and cannot eat, and have the self-control to stick to those restrictions.
What Can You Eat on the Keto Diet?
So what’s left? Traditionally healthy vegetables like kale, broccoli, brussel sprouts, and bell peppers are rich in carbs and must be limited. Protein found in fish, eggs, poultry, and lean meats are consumed in moderation to maintain muscle mass. Foods with high fat content, like seeds, nuts, avocados, oils, and butter, are consumed in the greatest amount. In fact, there is essentially no limit to these foods on the keto diet. If more fat than the body needs is consumed, it will be stored the same as if it were carbs.
Maintaining a properly balanced diet can be challenging when the majority of a food group (and its associated vitamins and nutrients) is eliminated. Restricted diets are healthy as long as key nutrients are still being consumed. A vegetarian can cut out red meat and its associated risks, but replace it with junk food like chips, french fries, and milkshakes. For example, carbs are a large source of daily fiber. Keto dieters should seek out keto diet-approved foods that also contain fiber such as avocados, nuts, and cauliflower.
Does It Work?
Many news articles and health magazines advertise quick weight loss using the keto diet. While this may be true for some people, there are no studies confirming this in healthy individuals. In a meta-analysis of 11 studies with 1,369 patients comparing low-carb and low-fat diets, the low-carb diets resulted in more weight loss but higher LDL (bad) cholesterol.2 The weight loss may be a short-lived benefit too, as the keto diet (which is low-carb and high-fat) is hard to stick to in the long term. Like other short term diets, many people gain their weight back after stopping the diet because they return to their previous eating habits. Long-term weight loss involves lifestyle changes such as breaking bad habits and establishing new habits that are possible to maintain.
Although the keto diet is a newer trend to lose weight in the general adult population, a ketogenic diet (in addition to medication) has been long been effective in reducing seizures in children with epilepsy. In one study, 38% of children on the ketogenic diet reduced their seizures by more than half.3 It should be noted that these children were monitored closely by their doctor and dietitians.
The keto diet is especially attractive to people with diabetes because it affects insulin levels as well as weight. Insulin is secreted when carbohydrates are eaten, so reducing carb intake reduces the need for insulin. One study found that the diet generally improves insulin sensitivity, and another reported improvements in controlling sugar levels and reduction of medications in diabetics.4,5
Our ability to lose weight is dependent on many individual factors like family history, sex, race, sleep, and where we live. It is important to recognize that what may work for one person may not work for another. The keto diet might not provide a net benefit for an otherwise healthy person.
What are the Risks?
There are risks to altering the way the body metabolizes its main source of energy. Diets rich in refined carbohydrates are linked to metabolic disorders such as nonalcoholic fatty liver disease (NAFLD) which is associated with Type II Diabetes and obesity.6 Losing weight if a person has any of these conditions is generally considered beneficial. However, replacing carbs with saturated fats may prove harmful. Certain fats raise cholesterol, which is associated with increased risk of heart disease.7 One longitudinal study found that both high and low carbohydrate diets had the highest mortality rates.8 This suggests that carbohydrates in moderation may be the most beneficial route to good health.
Additionally, the first week of the keto diet may bring what’s called the “keto flu”. It’s not contagious or permanent, but the body shifting from one source of energy to another sometimes causes fatigue, headache, brain fog, nausea, and muscle cramps.
The Bottom Line
While dropping weight quickly is always tempting, it is important to consider both the health benefits and risks of certain diets. Talking with your doctor about the best approach to lose weight with your health history in mind is always a good idea. Long-term success can be found in reducing refined carbs and cutting processed foods, and replacing them with fresh fruits and vegetables, lean protein, and exercising.
- Fine Eugene J, Feinman Richard D. Thermodynamics of weight loss diets. Nutrition & metabolism. 2004;1(1):15-15. doi:10.1186/1743-7075-1-15
- Mansoor N, Vinknes KJ, Veierød MB, Retterstøl K. Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. The british journal of nutrition. 2016;115(3):466-479. doi:10.1017/S0007114515004699
- Neal EG, Chaffe H, Schwartz RH, et al. The ketogenic diet for the treatment of childhood epilepsy: a randomised controlled trial. The lancet neurology. 2008;7(6):500-506. doi:10.1016/S1474-4422(08)70092-9
- Brinkworth GD, Wycherley TP, Noakes M, Buckley JD, Clifton PM. Long-term effects of a very-low-carbohydrate weight-loss diet and an isocaloric low-fat diet on bone health in obese adults. Nutrition. 2016;32(9):1033-1036. doi:10.1016/j.nut.2016.03.003
- Eric C Westman, William S Yancy, John C Mavropoulos, Megan Marquart, Jennifer R McDuffie. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrition & metabolism. 2008;5:36-36. doi:10.1186/1743-7075-5-36.
- Asrih M, Jornayvaz FR. Diets and nonalcoholic fatty liver disease: the good and the bad. Clinical nutrition. 2014;33(2):186-190. doi:10.1016/j.clnu.2013.11.003
- Peters SAE, Singhateh Y, Mackay D, Huxley RR, Woodward M. Total cholesterol as a risk factor for coronary heart disease and stroke in women compared with men: a systematic review and meta-analysis. Atherosclerosis. 2016;248:123-131. doi:10.1016/j.atherosclerosis.2016.03.016
- Seidelmann SB, Claggett B, Cheng S, et al. Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. The lancet public health. 2018;3(9):428. doi:10.1016/S2468-2667(18)30135-X