Keto FAQ: 28 questions answered
June 11, 2026 · 7 min read
The questions that come up most on keto, answered in plain language. Links go deeper where more detail helps.
What keto is and how it works
What is a ketogenic diet? A ketogenic diet keeps carbohydrate intake very low — usually under 20 to 50 grams of net carbs a day — so the body depletes glucose stores and shifts to burning fat. The fat breakdown produces ketone bodies, which fuel the brain and muscles instead of glucose. See what is ketosis for the mechanism.
What is ketosis? Ketosis is the metabolic state where the body is running primarily on fat and ketones rather than glucose. Blood beta-hydroxybutyrate (BHB) of 0.5 mmol/L or higher is the common threshold. It is not dangerous in healthy people — it's a normal adaptive response to low carbohydrate availability.
How is keto different from just eating low-carb? Degree. Low-carb diets typically restrict carbs to under 100–150g a day; keto restricts to under 50g (often under 20g) to reliably enter ketosis. The distinction matters because ketosis requires a specific threshold, not just "fewer carbs."
What are net carbs? Total carbohydrate minus fiber and most sugar alcohols. Fiber and erythritol don't raise blood glucose meaningfully, so they're subtracted. Maltitol does raise blood glucose and should not be fully subtracted. See the net carbs explainer.
Getting started
How do I start keto? Set a net-carb ceiling (most beginners start at 20–30g), remove obvious carbs from the kitchen (bread, pasta, rice, sugar, most fruit), and track that one number for the first week. The beginner guide covers the full setup.
What can I eat on keto? Protein (meat, fish, eggs), non-starchy vegetables (spinach, broccoli, cauliflower, zucchini), healthy fats (olive oil, butter, avocado), and full-fat dairy. The keto food list sorts the categories.
What foods are off-limits? Grains (bread, pasta, rice, oats), starchy vegetables (potatoes, corn), sugar, most fruit, and most beans. These push net carbs past the ketosis threshold quickly.
How long does it take to get into ketosis? Most people reach measurable ketosis (blood BHB ≥ 0.5 mmol/L) in two to four days of holding net carbs under 20–30g. A hidden carb source is the most common reason it takes longer. Fasting or exercise can accelerate it.
What is the keto flu and how do I avoid it? A cluster of transient symptoms — fatigue, headache, irritability, muscle cramps — that appear in the first two to three days and typically resolve within one to two weeks. Caused largely by electrolyte and fluid shifts as insulin drops. Drinking more water and adding salt, potassium, and magnesium helps. See the keto flu guide.
Tracking and macros
How do I track net carbs? Log meals using a method fast enough to sustain daily. Options: a voice-first app (speak the meal, get the carbs), a food database app with barcode scanning, or the plate method for repeat meals. The tracking guide covers each. Speed is what makes tracking last.
Do I need to count calories on keto? Not necessarily at first — many people lose weight on keto without explicit calorie counting because the high fat and protein intake reduces appetite. If weight stalls despite staying in ketosis, a calorie audit is usually the next step.
What are the right keto macros? A rough starting split: 70–75% of calories from fat, 20–25% protein, and 5% carbs. In practice, the carb ceiling (20–50g net) is the number that governs ketosis. Fat and protein percentages matter for satiety and muscle retention but don't decide whether you're in ketosis. See keto macros.
Do I need a food scale? No. The tracking without weighing guide covers visual estimates and the plate method, which work for most people most of the time. A scale is useful if you're debugging a stall.
How do I track restaurant meals? Estimate from the components. Protein + non-starchy vegetables + fat is the base; the carbs are in sauces and sides. Describing the plate to Copper Keto Companion gives an estimate as fast as any method. The eating out guide covers the ordering pattern.
Staying in ketosis
How do I know if I'm in ketosis? Testing is the only way to confirm. A blood ketone meter measuring BHB is the most accurate; 0.5 mmol/L or higher means you're in ketosis. Urine strips work early on but become less reliable after keto-adaptation. See how to test for ketosis.
What breaks ketosis? Too many carbs — usually from hidden sources. Maltitol in "sugar-free" snacks, sugar in sauces, portion creep in calorie-dense foods like nuts and cheese. Excess protein can also blunt ketosis in some people via gluconeogenesis, though for most people adequate protein is fine. See hidden carbs on keto.
Does alcohol break ketosis? Pure spirits (vodka, whiskey, gin) have zero carbs and won't directly kick you out of ketosis, but alcohol pauses fat metabolism while the liver processes it, slowing ketone production. Beer and sweet wine carry carbs and will raise blood glucose. A glass here or there matters less than consistency over the week.
Can I eat too much protein on keto? For most people, adequate protein does not prevent ketosis. The concern about protein converting to glucose (gluconeogenesis) is real but overstated in practice — the body produces glucose from protein on demand, not simply because protein is present. Eat enough protein to preserve muscle; don't undershoot it from fear.
When the scale stalls
Why did I stop losing weight on keto? Usually one of five things: hidden carbs pushing you over your ceiling, portions that drifted upward, water retention masking fat loss, not actually being in ketosis, or normal rate-of-loss slowdown after rapid early loss. Work through the stall checklist in that order.
How long is a normal keto plateau? One to two weeks of flat readings is ordinary variance. Three or more weeks with tight tracking is worth investigating. See the keto stall guide.
How do I break a keto plateau? Start with the checklist above. Most plateaus resolve when hidden carbs or portion drift are found and corrected. If tracking is genuinely tight and ketosis is confirmed, rechecking total calorie intake is the next step.
Why do I keep quitting keto? Usually because the logging method is too slow to sustain. Week three is when novelty fades and logging friction catches up. The fix is a faster tracking method, not more discipline. See why people quit keto in week three.
Sugar alcohols, fiber, and specifics
Are all sugar alcohols free on keto? No. Erythritol has a glycemic index near zero and is generally safe to subtract. Maltitol has a glycemic index of roughly 36–52 and does raise blood glucose — subtracting it understates the real carb count. The full guide covers each common sugar alcohol.
Does fiber raise blood sugar? Largely no, which is why it's subtracted in the net-carb calculation. Higher fiber intake is also associated with other health benefits. The carb science research collects the sourced evidence.
Can I eat fruit on keto? Most fruit is too high in sugar for a standard keto ceiling. Exceptions: berries (strawberries, raspberries, blackberries) in small portions — a quarter to half cup fits in most ceilings. Avoid bananas, grapes, mango, apples at normal serving sizes.
What can I drink on keto? Water, black coffee, unsweetened tea, and sparkling water are all zero carbs. Heavy cream in coffee is nearly zero. Avoid fruit juice, regular soda, sweetened lattes, and most mixed drinks. The keto Starbucks guide covers coffee shop ordering specifically.
Frequently asked
Is keto safe long-term? For most healthy adults, yes — the evidence on long-term keto is still developing, and it's not the right approach for everyone. The research index collects the actual studies, including the ones with mixed findings. If you have a medical condition, talk to your doctor before starting.
Do I need to exercise on keto? No — keto works without exercise, and fat loss comes from diet more than movement. Exercise can accelerate glycogen depletion and help with stalls, but it's not required.
How do I eat at restaurants on keto? One rule: protein, non-starchy vegetables, keep the fat, skip the starch and sweet sauces. Works at almost any restaurant. The eating out guide covers the pattern by cuisine, and Chipotle and Starbucks have their own guides.