Chances are you may have heard of the ketogenic diet recently. Maybe you have only heard the phrase “keto”, or “ketosis”, or “ketones”. Maybe you have no idea what any of these phrases mean! This is where we are here to help. We will clarify some terminology, exam the ketogenic diet, and see why this diet has become the latest trend in weight loss.

1

What is the Ketogenic Diet?

First, a few terms. Ketosis refers to the mild form of ketoacidosis which a high level of ketones in blood and urine. Ketones are the byproduct of fat metabolism excreted from the body via the kidneys..A side effect of ketosis can be poor appetite. the state of high amounts of ketone bodies present in the blood resulting from breakdown of fatty acids and amino acids. Can cause damage to kidneys.

According to The Epilepsy Foundation, a ketogenic diet is a high fat, low carbohydrate diet prescribed by doctors who specialize in seizures, is managed by a dietitian, and is used when seizure medication fails. The typical ratio of nutrients is 3:1:1 of fat, carbs, and protein grams respectively. Although having ketones is the body is not typically dangerous, it is important to have them measured via urine, blood, and breath when on a ketogenic diet to avoid ketoacidosis. A ketogenic diet has also been consistently shown in research to help manage seizure activity in those with epilepsy. This is thought to be due to the fact that the brain’s main source of nutrition is glucose. With an increase in amounts of glucose going to the brain, the increase in seizure activity.

 

So Why is Keto so Popular Now?

Low-carbohydrate diets are nothing new. The early 2000’s saw the boom of the Atkin’s diet, which is also low carb, high protein and relies on the body to go into a ketogenic state in order to lose weight. Another new food “fad” is the Paleo Diet, consisting of high protein foods and limiting refined foods and fruit, in order to resemble the diet of Paleolithic humans, as means of overall healthier eating. The raves of the ketogenic diet can be supported by the research in showing that, yes, it is shown to contribute to weight loss. Carbohydrates are a very common source of calories in the American diet and added sugars are also the first to be blamed for obesity (see our article on sugar here) and intake should be monitored by those with diabetes. The American Diabetes Association recommends 45-60 grams of carbohydrates per meal, whereas some of the ketogenic diets used below consisted of <60 grams for the entire day. By subtracting these extra calories from your diet {think super-sized portions of pasta, sodas, and juices), weight loss is almost inevitable. However, having too low of carbohydrate intake can be dangerous for diabetics, leading to hypoglycemia. Diets high and fat are usually not recommended for weight loss in that fat is very high in calories compared to carbohydrates and protein, and increases risk of heart disease. With these known practices and dietary recommendations, it is important to understand why the ketogenic diet is now used for weight loss.

 

Ketogenic Diet and Weight Loss

There are a number of studies on the ketogenic diet in relation to weight loss. A majority of them finding that, indeed, a very low carbohydrate low calorie diet (typically <80 grams/day) results in significant weight loss, decreased Hemoglobin A1c, and improved cardiac lab values. There is some common sense to these results, if you are not eating carbohydrates, your blood sugar will not rise. If you are taking in less calories than you are putting out, you will lose weight, especially when it is less than 1,000 calories provided in most of the studies. Most of these studies analyse the ketogenic diet in the short term, typically less than four months. One study attempted to show long term weight loss for one year following the keto diet, however, it was only followed in stage 2 of 7 of the year long process, being replaced with the Mediterranean diet [1]. Another study replaced the ketogenic diets with balanced, inclusive diets after 30-45 days [ 2]. A missing element to these studies is exercise. Increase in exercise can also result in weight loss, lower cholesterol, and lower blood sugars. In a typical calorie-reduction weight loss plan, exercise is a key component, which was not noted to be used in these studies. A majority of these studies, the protein source used was that of a “protein preparation” that was provided to the participants. Some of the studies were also funded by the company who provided the protein supplements. In the real world, it is much easier to eat a protein bar or drink a high protein shake than to actually eat the protein gram equivalent of real food. [2]

A positive in most of the studies is that there was little evidence of impaired renal function when follow a keto diet short term. Too much protein intake in the body can result in overworking of the kidney, causing damage. Protein amounts were calculated using a range of 0.8-1.2 gm/kg in most studies, which is not an extreme amount per day (for example, a 60 kg person would be 79 gm protein per day). Also, with a low amount of total calories consumed, protein intake was not used as a percentage of total calories, but as a calculated amount based on weight. It’s fairly common to see non-research based versions of keto diet recommending 2 gm/kg of protein, which can be upwards of 150-200 gm protein per day, which could cause kidney damage. Again, let me emphasize that high protein intake was short term and these subjects did not have pre-existing kidney dysfunction [1, 2] . Another positive outcome in most studies is an increase in HDL cholesterol, the “good” cholesterol. This makes since in that plant-based oil were included in the keto diets, which likely were not part of the previous diet of the participants. An increase in fiber-rich vegetables, also included in the keto diets, can also explain the decrease in VLDL and LDL cholesterol [3, 4].

It’s important to note these studies did not use the traditional “ketogenic diet” of high fat, low carbohydrate that is suggested to manage seizures, but focuses solely on very low carbohydrate and very low calorie in order to lose weight. With any elimination diet, or in this case “very low carb” diet, there is a risk of potential vitamin and mineral deficiency. Limiting fruits and some grains can result in lower intake of Vitamin C, folate, and potassium. Many limiting factors of these studies included limited criteria of subjects, short length of study, and actually analysing true satisfaction of diet adherence [2].

 

Conclusion

So is the ketogenic diet just a new Atkins? Not necessarily. In the similarity that they are both low carb, the ketogenic diets used in the studies emphasize non-starchy vegetable intake and heart healthy oils, known components of a general, healthy diet. In the research available, there is evidence showing very low carbohydrate diets are very effective in short-term weight loss, but these are all also paired with extremely low calorie intakes. Evidence supporting very low carbohydrate intake in the long term (>1 year) is still needed to show effectiveness. In general, diabetics should be monitoring, counting, and limiting carbohydrate intake to some degree in efforts to monitor Hemoglobin A1c and blood glucose levels to avoid hypoglycemia and diabetic ketoacidosis. Generally, people who are obese have an excessive calorie intake, thus when carbohydrate intake is limited, which was previously majority of total calorie intake, significant weight loss is expected. Overall, limiting carbohydrate and total calorie leads to weight loss and should be thoroughly discussed with a doctor, and dietitian, before starting. Adequate overall nutrient intake should be emphasized, and long term weight loss goals and maintenance should be part of any weight loss program. Below are more research articles that involve studying the ketogenic diet in relation to obesity and weight loss.

 

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

The effects of low carbohydrate diets on liver function tests in nonalcoholic fatty liver disease: A systematic review and meta-analysis of clinical trials

Effect of type and amount of dietary carbohydrate on biomarkers of glucose homeostasis and C reactive protein in overweight or obese adults: results from the OmniCarb trial

Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review

Ketogenic Diet for Obesity: Friend or Foe?

Comparison of a very low-calorie-ketogenic diet with a standard low-calorie diet in the treatment of obesity

Do ketogenic diets really suppress appetite? A systematic review and meta-analysis

The effect of dietary protein restriction on the progression of diabetic and nondiabetic renal diseases: a meta-analysis