Review of Diets: Ketogenic Diets for Losing Weight

For centuries, people have used the ketogenic or "keto" diet—a low-carb, high-fat eating plan—to treat a variety of medical conditions. The ketogenic diet was widely used to treat diabetes in the 19th century. It was first made available in 1920 as a successful treatment for epilepsy in kids who did not respond well to medication. Additionally, the ketogenic diet has been tried and tested in closely watched situations for diabetes, polycystic ovarian syndrome, Alzheimer's disease, and cancer.

But because of the low-carb diet craze that began in the 1970s with the Atkins diet (a very low-carbohydrate, high-protein diet that was a commercial success and popularized low-carb diets to a new level), this diet is receiving a lot of attention as a viable weight-loss strategy. These days, there are other low-carb diets that are high in protein but moderate in fat, such as the Paleo, South Beach, and Dukan diets. On the other hand, the ketogenic diet stands out due to its unusually high fat content, usually between 70% and 80%, while only consuming a moderate amount of protein.

How it works?

The idea behind the ketogenic diet for weight loss is that when you deprive the body of glucose, which is the body's primary fuel and is produced by eating carbohydrates, your body will produce ketones, or alternative fuel, from stored fat. Hence the term "keto"-genic.

 

Because it cannot store glucose, the brain has the highest daily requirement, requiring about 120 grams of glucose. When very little carbohydrates are consumed, such as during a fast, the body first releases glucose from stored glucose in the liver and briefly breaks down muscle. The body starts using fat as its main fuel if this keeps up for three to four days and all of the stored glucose is used up. Insulin levels in the blood also drop at that point. In the absence of glucose, the liver can use fat to produce ketone bodies.

Ketosis is the term for the state in which ketone bodies build up in the blood. When engaging in extremely intense exercise and fasting (such as sleeping through the night), healthy individuals naturally enter a state of mild ketosis. According to proponents of the ketogenic diet, blood levels of ketones shouldn't rise to dangerous levels (referred to as "ketoacidosis") if the diet is properly followed because the brain will use them as fuel and healthy people will normally produce enough insulin to keep excessive ketones from forming.

Each person experiences ketosis at a different rate, and the amount of ketone bodies that build up in the blood varies depending on body fat percentage and resting metabolic rate, among other variables.

Describe ketoacidosis

Ketoacidosis is a potentially fatal blood acidity state that can result from an overabundance of ketone bodies. The kidneys start excreting ketone bodies and bodily water in the urine during ketoacidosis, which can lead to some fluid-related weight loss.

Because type 1 diabetics do not produce insulin, a hormone that inhibits the overproduction of ketones, ketoacidosis most frequently affects them. On the other hand, ketoacidosis has been documented to happen in a small number of non-diabetic people after a protracted, extremely low-carb diet.

The Diet

There isn't just one “standard” ketogenic diet that calls for a particular macronutrient (fat, protein, and carb) ratio. A medium plain bagel contains less than 50 grams of carbohydrates per day, and the ketogenic diet can lower intake of carbohydrates to as little as 20 grams. Popular ketogenic resources generally recommend consuming 70–80% fat from total calories, 5–10% carbs, and 10–20% protein on average each day.

This corresponds to roughly 165 grams of fat, 40 grams of carbohydrates, and 75 grams of protein for a diet of 2000 calories. In contrast to other low-carb, high-protein diets, the protein allowance on the ketogenic diet is moderate because an excess of protein can interfere with the process of entering ketosis. A ketogenic diet calls for consuming enough protein to maintain lean body mass, including muscle, but this will still put you in ketosis because the amino acids in protein can be converted to glucose.

Though they vary widely, all ketogenic diets prohibit foods high in carbohydrates. Fruit juices, potatoes, corn, and other starchy vegetables, as well as starches from whole and refined grains like breads, cereals, pasta, rice, and cookies, may be among the foods that are readily apparent.

Legumes, beans, and most fruits are among those that might not be as apparent. Foods high in saturated fat, like processed meats, butter, lard, and fatty cuts of meat, as well as foods high in unsaturated fat, like nuts, seeds, avocados, plant oils, and oily fish, are generally permitted on ketogenic diets. Keto food lists can differ and even contradict each other, depending on where you learned about them.

Programs advise a ketogenic diet to be followed until the targeted weight is lost. Once this is accomplished, one can follow the diet for a few days a week or a few weeks each month, alternating with other days that allow a higher carbohydrate intake, to prevent weight regain.

In the short term, the ketogenic diet has been demonstrated to result in positive metabolic changes. Health indicators linked to being overweight, such as insulin resistance, high blood pressure, and elevated cholesterol and triglycerides, have improved along with weight loss.

The use of low-carb diets, such as the ketogenic diet, to treat type 2 diabetes is also gaining popularity. There are a number of theories explaining why the ketogenic diet aids in weight loss, though none of them has been proved by studies: 

- A satiating effect with decreased food cravings due to the high-fat content of the diet.

- A decrease in appetite-stimulating hormones, such as insulin and ghrelin, when eating restricted amounts of carbohydrate.

- A direct hunger-reducing role of ketone bodies—the body’s main fuel source on the diet.

- Increased calorie expenditure due to the metabolic effects of converting fat and protein to glucose.

- Promotion of fat loss versus lean body mass, partly due to decreased insulin levels.

Potential Pitfalls

Maintaining a very high-fat diet can be difficult. Extreme carbohydrate restriction may cause hunger, exhaustion, low mood, irritability, constipation, headaches, and "fog" in the brain. These symptoms can linger for days or weeks. Even though these uneasy sensations might pass, there might be new difficulties in finding satisfaction in the small selection of foods and in being unable to eat things that you would normally enjoy, like a creamy sweet potato or a crunchy apple.

Long-term ketogenic diets may have unfavorable side effects, such as elevated blood levels of uric acid (a risk factor for gout) and an increased risk of kidney stones and osteoporosis. If a number of the foods that are suggested on the ketogenic diet are not consumed, possible nutrient deficiencies could result.

To make sure you are getting enough fiber, B vitamins, and minerals (iron, magnesium, zinc), which are generally found in whole grains and other diet-restricted foods, it is important to include a variety of these foods in your diet every day in addition to high-fat foods. A registered dietitian's help may be helpful in developing a ketogenic diet that minimizes nutrient deficiencies because entire food groups are excluded.