Dietary plans are high-yield topics on the exam, as they can test your understanding of associated macronutrients, health benefits or potential risks, and any special monitoring needed. While the ABOM will not endorse any specific dietary pattern, they will expect you to know who may benefit most from each plan and who may be harmed. The ketogenic dietary pattern, by definition, is a variant of the low-carbohydrate diet. This blog will cover most of the important aspects and what will be expected on this topic come test day.

Low-carbohydrate diets have been popular for years and incorporated to varying degrees through Atkins, low-glycemic index, ketogenic, and South Beach diets. As with any dietary plan, sustainability is the long-term goal, which can be particularly challenging with extreme consumption or restriction of a particular macronutrient. Regardless of the macronutrient composition, there must be an overall caloric deficit to promote weight loss.

The very low-calorie ketogenic diet was initially developed in the 1920s to reduce seizures in children with recalcitrant seizures, but has subsequently been used to promote weight loss. The ketogenic dietary pattern promotes the utilization of stored fat for energy. With the degradation of stored fats to produce energy, ketones are produced as a byproduct. Ketones are one of the energy sources for the brain in those who have insufficient glucose intake, so patients sometimes claim to be able to think more clearly while in persistent ketosis. Also, similarly to those who are in starvation ketosis or diabetic ketoacidosis, ketones tend to blunt appetite, and patients often state they have less hunger and increased satiety.

The ketogenic pattern has different phases, with the first being the induction phase. During this initial period, carbohydrate ingestion is significantly reduced to ≤20 grams per day, consisting primarily of non-starchy vegetables. Protein intake is increased to induce ketosis. Over time, a slightly wider variety of nuts, low glycemic whole fruits, etc., can slowly be added. Once weight loss goals are achieved, a maintenance phase can begin, during which legumes, whole grains, and whole fruits can be introduced, along with a gradual increase in carbohydrate intake to 60-90 grams.

An important thing to keep in mind, is the safety of the keto diet in certain populations. Those who are more likely to develop ketoacidosis should avoid this dietary plan or, at minimum, require very close monitoring. For example, those on an SGLT-2 inhibitor already have a higher risk of developing euglycemic ketoacidosis. By inducing dietary ketosis, this risk may increase significantly. Those requiring insulin, including patients with type 1 diabetes, are also at risk (as well as at an increased risk of hypoglycemia) when significantly deprived of carbohydrates. In addition, a ketogenic dietary pattern, along with obesity itself, places patients at an increased risk of a prolonged QTc, which may develop into Torsades de Pointes. Although this arrhythmia is rare, reviewing medications and cardiac history would be an important step before recommending this diet to reduce this potentially deadly complication.

The ketogenic plan also has a few interesting nutritional concepts. Patients often replace carbohydrates with higher intakes of protein that may contain more saturated fats, cholesterol, and red meat. Therefore, patients may notice increased LDL and total cholesterol levels after initiating this plan. HDL levels tend to also increase, whereas triglycerides, with less glucose intake, tend to decrease. In 2023, the American College of Cardiology suggested long-term keto-like dietary patterns with high-fat and low-carbohydrate intake carry a 2- fold increased risk of cardiovascular disease due to these lipid abnormalities. Reducing saturated fats and exchanging for polyunsaturated fats is a compromise suggested to mitigate this risk. In addition, selenium, which is found in insufficient amounts in fattier foods, may become deficient. Prolonged depletion of selenium could cause cardiomyopathy, a testable complication of selenium deficiency.

Finally, be familiar with electrolyte changes. The initial transition into ketosis has a significant diuretic effect. With increased urination comes the early, rapid water weight loss that is not attributable to fat loss. This diuresis promotes urinary wasting of sodium, potassium, and magnesium, so if electrolyte abnormalities occur, hyponatremia, hypokalemia, and hypomagnesemia may be seen. Uric acid levels may also rise initially due to diuresis and increased protein intake; however, a recent meta-analysis did not show an increased risk of gout associated with ketogenic diets.

On test day, know the most common dietary patterns and their downstream effects. Lab findings/abnormalities, complications, risks, and who may benefit from each plan are all fair game. Clinically, dietary preferences vary greatly. Focus on patient education that promotes long-term, sustainable dietary patterns that produce long-standing results. For some, the ketogenic dietary plan may meet those criteria, while the restrictions may cause this to be short-lived for others.

Sample Question

A 47-year-old woman with hyperlipidemia and prediabetes presents to her primary care physician because she is not tolerating statin therapy. She would prefer to pursue dietary modifications rather than medication for primary cardiovascular prevention. She is planning to start on a ketogenic diet. Three months from now, how would her laboratory work be expected to change?

A. Decreased HDL

B. Increase in TG

C. Increase in LDL

D. Decreased total cholesterol

Next Week: Everything to know about metformin

Following Week: Monthly Knowledge Check. This is a review checklist of must-know items for ABOM exams based on the previous four blog topics (One-anastomosis gastric bypass, Alström syndrome, ketogenic dietary pattern, and metformin). In addition, this will include a brief explanation of the correct answers to previous sample questions.

Upcoming Weeks: Updated pediatric guidelines, polycystic ovarian disease, telogen effluvium, and intensity of exercise/METS

For more practice questions, check out the following:

  • Obesity Medicine Board Review Questions (2026): Qs 47, 159, 258, and 263.
  • Obesity Medicine Practice Tests (2026): Qs 60, 83, 99, 126, 145, 257, 321, and 349.

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