Ketogenic Diet
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40 free Ketogenic Diet trivia questions with answers — trivia quiz, new questions added Oct 2026.
The ketogenic diet swaps almost all carbohydrate for fat, pushing the body into a state called ketosis in which it runs on ketones. It began as a medical therapy a century ago, long before it became a popular weight-loss plan, and its story takes in hospital wards, Hollywood and Arctic exploration. This quiz covers the science of ketosis in plain terms, the foods that do and do not fit a keto kitchen, the doctors and writers who shaped low-carb eating, and the side effects that researchers watch for. Expect questions on what the body burns for fuel, on popular low-carb swaps for bread, pasta and sugar, and on a few surprising chapters of the diet's history. It is written for keto beginners checking what they know, for nutrition and health classes, and for quiz hosts who want a food round with some science in it. Every answer comes with a short explanation, so you learn why each fact holds as you play.
30 of 40 questions with answers and explanations. Play the quiz
Q 01The ketogenic diet was developed by doctors in the 1920s to treat which neurological condition in children?
Epilepsy
Epilepsy drugs such as phenytoin pushed the diet aside from 1938, and it stayed out of fashion until the 1990s.
Q 02Which solvent gives the fruity smell of so-called keto breath?
Acetone
Acetone, the solvent in nail polish remover, is one of the three ketone bodies, and it is so volatile that the body gets rid of it through the lungs.
Q 03Which vegetable do keto cooks pulse into rice, mash like potatoes and bake into pizza crust?
Cauliflower
Cauliflower is 92% water and only about 5% carbohydrate, which is why it can stand in for so many starchy staples.
Q 04Bulletproof coffee, inspired by a traditional tea its creator drank in Tibet, is blended with which dairy product?
Butter
Butter went into Dave Asprey's morning coffee after he tasted Tibetan tea made with yak fat, and he posted the recipe on his blog in 2009.
Q 05A typical keto limit of 50 grams of carbohydrate a day is less than the amount in one medium plain what?
Bagel
Bagel fans face the starkest cut: one medium plain one holds more carbohydrate than a whole day's keto allowance, and stricter plans go as low as 20 grams.
Q 06Keto dieters at In-N-Out can order a burger Protein Style, which replaces the bun with large leaves of what?
Lettuce
Lettuce has wrapped In-N-Out's bunless Protein Style burgers since the 1970s, one of the unadvertised options on the chain's so-called secret menu.
Q 07Which Oscar winner played a mother seeking ketogenic treatment for her son in the 1997 TV film ...First Do No Harm?
Meryl Streep
Meryl Streep earned Emmy and Golden Globe nominations for the role, in a story that director Jim Abrahams drew from his own son Charlie's experience.
Q 08Which popular snack, botanically a legume and not a true nut, sits on Harvard's keto not-allowed list?
Peanuts
Peanuts are ruled out alongside beans and lentils on strict keto food lists, while tree nuts such as pecans and walnuts are welcome.
Q 09Which organ turns fat into the ketone bodies that fuel the body when carbohydrates run low?
Liver
The liver makes ketone bodies from fat but lacks the enzyme needed to burn them, so it ships them all out for other tissues to use.
Q 10Which hormone falls after a few days of carbohydrate restriction, signalling the body to switch to burning fat?
Insulin
Insulin normally tells the body to store fuel; when levels drop, fat cells release their fatty acids into the blood to be burned instead.
Q 11On a ketogenic diet, ketone bodies stand in for which sugar that is normally the main energy source for cells?
Glucose
Glucose reserves are small: after three to four days without carbohydrate they are fully depleted, and the body turns to fat for fuel.
Q 12Unlike fatty acids, ketone bodies can cross a protective barrier in the bloodstream to fuel which organ?
Brain
The brain cannot burn fatty acids directly, yet after about 24 days without food ketone bodies supply up to two-thirds of its fuel.
Q 13Ketoacidosis, a dangerous blood condition often confused with ketosis, most commonly affects people with which illness?
Type 1 diabetes
Type 1 diabetes leaves ketone production unchecked, so blood levels can pass 10 millimolar, against roughly 0.5 to 3 in the ketosis of a low-carb diet.
Q 21Which nut is ground into the meal that has become a baking staple for people on low-carbohydrate diets?
Almond
Almond meal was a pastry ingredient long before keto: it goes into French macarons and frangipane, and it is one of the two main ingredients of marzipan.
Q 22Shirataki noodles, a very low-calorie pasta swap whose name means white waterfall, are made from which plant?
Konjac
Konjac noodles are 97% water and only 3% plant matter, taken from the underground stem of a species also known as devil's tongue.
Q 23Which zero-calorie sugar substitute comes from the leaves of a plant native to Paraguay and Brazil?
Stevia
Stevia's plant was called sweet herb by the Guaraní peoples of South America, who used the leaves for centuries to sweeten their teas.
Q 14Which stored carbohydrate, held in muscle with three to four parts water, must run low before ketosis begins?
Glycogen
Glycogen is the body's quick-access carbohydrate reserve, and the stores are typically used up within the first 24 hours without food.
Q 15Doctors devised the ketogenic diet in 1921 to imitate the metabolic effects of which far older medical remedy?
Fasting
Fasting had been prescribed since ancient Greece, but no patient can keep it up; Russell Wilder wanted its benefits in a form that could be maintained indefinitely.
Q 16Russell Wilder coined the term ketogenic diet in 1921 while working as a physician at which American medical centre?
Mayo Clinic
Mayo Clinic paediatrician Mynie Peterman then fixed the classic recipe: a gram of protein per kilo of body weight, 10 to 15 grams of carbohydrate a day, and fat for everything else.
Q 17Which cardiologist turned low-carbohydrate eating into a 1970s craze with his bestselling book Diet Revolution?
Robert Atkins
Robert Atkins based the 1972 bestseller on a regime he had been prescribing to his own patients through the 1960s.
Q 18Keto dieters calculate net carbs by subtracting sugar alcohols and which other nutrient from total carbohydrates?
Fiber
Fiber passes through the gut unabsorbed, though Harvard warns that net carbs is an unregulated term invented by food manufacturers as a marketing strategy.
Q 19MCT oil, prized on keto because it yields more ketones than other fats, comes from the oil of which plant?
Coconut
Coconut oil is rich in medium-chain fats, which are absorbed more quickly than ordinary long-chain ones; a 1971 hospital keto diet drew 60% of its calories from MCT oil.
Q 20Which fruit is a keto favourite because about 75% of its energy comes from fat, mostly the monounsaturated kind?
Avocado
Avocado flesh is about 15% fat, a markedly higher share than most other fruit, which made it a staple wherever meat and dairy were hard to come by.
Q 24Which nut, first farmed on a large scale in Hawaii, is prized on keto because it is about 76% fat?
Macadamia
Macadamia trees are native to Australia, the only widely grown food plant that is, yet Hawaii was the world's largest producer for more than a century.
Q 25Which crunchy snack, known in Mexico as chicharrones, is a low-carbohydrate alternative to potato chips?
Pork rinds
Pork rinds are fried pig skin, so a serving has almost no starch and, by one magazine's count, nine times the protein of potato chips.
Q 26Full-fat milk is restricted on keto, though hard cheeses are often allowed, because milk is high in which natural sugar?
Lactose
Lactose also puts cream and ice cream on the restricted list, while hard cheeses pass because they contain far less of it.
Q 27Which fruits does Harvard's keto guide allow in small portions because they are lower in net carbs than others?
Berries
Berries are the exception to a strict rule: most other fruits, and every fruit juice, sit on the guide's not-allowed list.
Q 28Keto programmes often recommend beef raised on which feed, said to offer slightly higher amounts of omega-3 fats?
Grass
Grass-fed beef is recommended over grain-fed by many keto programmes, and free-range poultry is suggested for the same omega-3 reason.
Q 29Which hospital, whose method of starting the ketogenic diet is widely copied, treated Charlie Abrahams in the 1990s?
Johns Hopkins
Johns Hopkins had kept offering the diet through its lean decades, and Charlie's father found it only through a reference in a guide for parents.
Q 30Children starting the classic ketogenic diet in hospital are first given small meals of which festive-sounding drink?
Eggnog
Eggnog, made to the hospital's ketogenic recipe, is served at one-third of a normal meal's calories on day one and two-thirds on day two, before solid keto meals begin.