Keto Timeline Calculator: How Long Should You Do Keto?

How long should you do keto? It depends on where you start, where you want to end up and how much you move. Rather than give you a vague “a few months”, we built a calculator that works it out for your own body: how many weeks it takes, what to eat each month and which of our meal plans fits you.

How the keto timeline calculator works

There is no magic in the maths, and we would rather show you than hide it. The calculator goes through five steps:

1. Your energy needs. We estimate how many calories your body burns at rest with the Mifflin-St Jeor equation, the formula dietitians use most often. If you enter your body fat percentage, we switch to the Katch-McArdle formula, which works from your lean mass instead.
2. Your activity. That resting number is multiplied by a standard activity factor, from 1.2 for a desk job up to 1.9 for athletes.
3. Your pace. For fat loss you choose 0.5, 0.75 or 1% of your body weight a week. Research on keeping muscle while dieting points to exactly this range. To build muscle you choose 0.25 or 0.5% a week.
4. Day by day. The calculator then simulates your weight day by day. As you get lighter your body needs less food, so progress naturally slows down a little. That is why it is more honest than a simple “lose 2 lb a week” sum.
5. Month by month. Every 30 days it picks a new calorie level to match your new weight. These steps match our 30-day meal plans, so each month has a plan code.

1. 1Energy at restMifflin-St Jeor, or Katch-McArdle with body fat
2. 2Times your activitya factor from 1.2 to 1.9
3. 3Minus your pace0.5 to 1% of your weight a week
4. 4Day by daylighter body, a little less food
5. 5Month by montha new calorie level and plan code

The result is an estimate with a range, never a promise. Hormones, sleep, stress, water and the odd birthday cake all move the scale. We also have a floor: the calculator never plans below 1,200 kcal a day for women or 1,500 kcal for men.

What a keto timeline looks like, week by week

Days 1 to 4: getting into ketosis. With 20 to 50 g of carbohydrate a day, most people reach ketosis within two to four days, according to the Cleveland Clinic. Some feel tired or headachy for a few days (the so-called keto flu). Salt, water and simple meals help. Our ketosis tips and tricks cover this in detail.

The good news: most people only go through the keto flu the first time they get into ketosis. Your body learns to switch between burning carbohydrate (glycolysis) and burning fat (ketosis), and the more often it has done it, the smoother the switch becomes. So a holiday or a slice of birthday cake does not mean starting from scratch.

Week 1: the quick drop. The scale often falls by 2 to 4 lb (1 to 2 kg) in the first week. Your body stores carbohydrate as glycogen, and every gram of glycogen holds several grams of water. As those stores empty, the water goes too (Kreitzman and colleagues, 1992). It is real weight, but it is not fat, and it comes straight back when you eat more carbs. The calculator includes this drop in week one.

Weeks 2 to 4: settling in. Energy usually returns, and the loss slows to a steady fat-loss pace. This is where most people give up because the scale is “only” moving 1 to 2 lb a week. That is the pace that works.

Month 2 onwards: steady and slower. Each month you weigh a little less, so you need a little less food. Recalculate every 30 days and move to the next plan when the calculator tells you to. Plateaus of one or two weeks are normal: water shifts can hide fat loss for a while.

Why keto is easier to stick to: less hunger, fewer cravings

Most diets do not fail on day one. They fail in week three, when you are hungry all the time. Eat less and your body fights back: it releases more of the hunger hormone ghrelin, and food starts to call you from every cupboard.

Keto works differently. A 2015 systematic review and meta-analysis of studies on ketogenic diets (Gibson and colleagues, Obesity Reviews) found that people in ketosis felt less hungry and had less desire to eat, even while losing weight. The researchers point out that the main win is what does not happen: the rise in appetite that normally comes with weight loss stays away, and ketosis itself is the most likely reason. A 2021 review of the research on ketogenic diets and appetite (Roekenes and Martins) adds that ketosis keeps ghrelin from climbing the way it does on other diets.

Cravings change too. In a two-year randomized trial with 270 adults (Martin and colleagues, 2011), the people on a low-carb diet saw bigger drops in cravings for carbohydrates and starches, and in their liking for sugary foods, than the people on a low-fat diet. They were also less bothered by hunger. Cravings tend to fade for the foods you stop eating, and on keto those are exactly the sweet and starchy ones that are hardest to resist.

The effect is modest, not magic, and everyone is different. But it shows up exactly when you need it: in the middle of losing weight.

And it does not have to taste like a diet. Keto keeps the things that make a meal satisfying: butter, cheese, cream, crisp chicken skin and a proper sauce. Fat carries flavor and protein keeps you full, so a plate like our satay chicken with crunchy salad, Ligurian chicken with olives and cherry tomatoes or sticky pork chops feels like dinner, not like a punishment. That is how our meal plans are built: real food you look forward to.

How much weight can you lose on keto in a month?

After the first week, a realistic month looks like this. Add the one-off water drop of 2 to 4 lb (1 to 2 kg) to your first month.

Starting weight	Gentle (0.5% a week)	Steady (0.75% a week)	Faster (1% a week)
150 lb (68 kg)	3 lb (1.5 kg)	5 lb (2.2 kg)	6.5 lb (3 kg)
180 lb (82 kg)	4 lb (1.8 kg)	6 lb (2.7 kg)	8 lb (3.6 kg)
220 lb (100 kg)	5 lb (2.2 kg)	7 lb (3.3 kg)	9.5 lb (4.3 kg)
260 lb (118 kg)	5.5 lb (2.6 kg)	8.5 lb (3.8 kg)	11 lb (5.1 kg)

Heavier bodies lose more in absolute terms, because 1% of 260 lb is a lot more than 1% of 150 lb. The evidence on keeping muscle while dieting points to 0.5 to 1% a week as the sweet spot. Faster than that and more of what you lose tends to be muscle.

How long does it take to lose 20 lb on keto? Three worked examples

These come straight out of the calculator, so you can check them yourself.

• A woman of 40, 5 ft 5 in (165 cm), lightly active, 180 lb to 160 lb at a steady pace: about 16 weeks (14 to 17 in real life), eating around 1,400 kcal a day. That is our L1400-3S plan with 3 meals and snacks. Going on to 150 lb takes about 26 weeks in total.
• A man of 45, 5 ft 11 in (180 cm), active, 240 lb to 200 lb at a steady pace: about 24 weeks, starting at 2,200 kcal a day and stepping down to 2,000 kcal as he gets lighter.
• A woman of 55, 5 ft 3 in (160 cm), mostly sitting, 165 lb to 143 lb (75 to 65 kg) at a gentle pace: about 33 weeks, but anywhere from 25 to 50. Her calories sit at our 1,200 kcal floor, so adding a daily walk makes the biggest difference here.

How long should you stay on keto?

For weight loss, the practical answer is: until you reach your goal, and then a planned way out. Most research on ketogenic diets for weight loss runs for weeks to about two years, and long-term data is limited. A large 2021 review in Frontiers in Nutrition weighs the benefits against possible risks, such as higher LDL cholesterol in some people and a diet low in fibre-rich foods if you are not careful. That is why every dinner in our meal plans comes with vegetables.

When you reach your goal weight, you have two good options:

• Stay keto at maintenance. Some people simply keep eating this way because they like how they feel. Eat enough to hold your new weight (the plan one or two levels above your last one), and have your blood work checked by your doctor now and then.
• Step out slowly. Add carbohydrate back 10 to 20 g at a time over a few weeks, starting with vegetables, berries and pulses. Expect the scale to go up 2 to 4 lb: that is glycogen and water coming back, not fat.

Keto for muscle: the Build timeline

Switch the calculator to Build muscle and it adds a small calorie surplus instead of a deficit. We will be honest: keto is not the fastest way to build muscle, and some studies find smaller gains than with a higher-carb diet. But a study in trained men found similar gains in muscle over ten weeks when calories and protein were matched, with more fat lost on keto. Two things matter most: enough protein, and training.

The International Society of Sports Nutrition recommends 1.4 to 2.0 g of protein per kg of body weight a day for people who train. Our Build plans give at least 22% of their calories from protein, which lands in or above that range, and allow up to 6% of calories as net carbs so you have a little fuel around training. Example: a man of 28, 5 ft 11 in, very active, going from 165 lb to 175 lb at the lean-gains pace needs about 25 weeks on around 3,200 kcal a day.

Your 30-day keto meal plan, matched to your result

Knowing your number is half the job. Eating it every day is the other half, so we turned our own recipes into two 30-day plans: Lean for fat loss and Build for muscle. The calculator gives you a plan code such as L1600-3S: Lean, 1,600 kcal a day, 3 meals, with snacks.

• Portions sized for you. Every day lands within 5% of your calorie level, with a minimum amount of protein and a maximum amount of net carbs.
• 2 or 3 meals, with or without snacks. Whatever suits your day.
• Cook once, eat twice. Tonight’s dinner is tomorrow’s lunch, so you cook once a day at most. Dishes include our Asian chicken with cauliflower and broccoli purée, chicken korma skewers and a proper Italian loaded frittata.
• Batch breakfasts and snacks. Bake once for the week, for example our milk bagels with a protein topping, and keep a tin of protein crisps nearby.
• Weekly shopping lists and prep plans, in grams and ounces, plus easy swaps for ingredients that are hard to find in the US.

After 30 days, come back to the calculator with your new weight. If your calorie level has changed, it shows your next plan code.

Want to be the first to try it? The plans are almost ready. Run the calculator above and sign up under your result: our subscribers get the first week of their own plan before the official release, free and with no strings attached.

Talk to your doctor first if this is you

Keto changes how your body handles insulin, fluids and some medicines. Please plan your timeline with your doctor or a registered dietitian if you are pregnant or breastfeeding, have kidney disease, have had an eating disorder, or take insulin or a diabetes medicine from the SGLT2 group (such as empagliflozin or dapagliflozin). The FDA warns that SGLT2 medicines can cause ketoacidosis, and a very low-carb diet raises that risk. If you tick that box in the calculator, it does not give you a plan and shows this advice instead. Taking any other medicine for diabetes or blood pressure? Tell your doctor before you start too: cutting carbs often lowers blood sugar and blood pressure quickly, so doses may need to change.

Keto timeline FAQ

How long does it take to lose 20 lb on keto?

For most people, around 3 to 5 months. Someone starting at 180 lb and losing at a steady pace needs about 16 weeks. Heavier and more active people get there faster, smaller and less active people take longer.

Why did I lose so much weight in the first week?

Mostly water. Cutting carbs empties your glycogen stores, and the water stored with them leaves too. Expect 2 to 4 lb (1 to 2 kg). Fat loss continues more slowly from week two.

Will I get the keto flu every time?

Usually not. Most people only feel it the first time they go into ketosis. After that, your body switches between burning carbohydrate (glycolysis) and burning fat (ketosis) much more smoothly, so getting back into ketosis after a break tends to be easy.

Does keto reduce hunger and cravings?

For many people, yes. A 2015 meta-analysis found that people in ketosis felt less hungry and had less desire to eat, even while losing weight, and a two-year trial found bigger drops in cravings for carbohydrates and sweets on a low-carb diet than on a low-fat diet. The effect is modest and varies from person to person.

How long should you stay on keto?

Until you reach your goal, then either stay keto at maintenance calories or add carbohydrate back slowly. Long-term research is limited, so if you plan to stay keto for more than a year, check your blood work with your doctor.

Can you build muscle on keto?

Yes, with resistance training, enough protein (1.4 to 2.0 g per kg a day) and a small calorie surplus. It tends to be a little slower than on a higher-carb diet, so choose the Build option and give it time.

Is the calculator accurate?

It is a good estimate, not a measurement. The formulas are the ones professionals use, but any individual can be 10% above or below them. That is why we show a range, and why you should recalculate every month with your real weight.

Can I share my result?

Yes. Use the share buttons under your result. The link opens your exact result, and “Save as image” creates a picture for your Instagram story or your fridge door.

Sources

• Gibson AA, Seimon RV, Lee CMY, et al. Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. Obes Rev, 2015.
• Roekenes J, Martins C. Ketogenic diets and appetite regulation. Curr Opin Clin Nutr Metab Care, 2021.
• Martin CK, Rosenbaum D, Han H, et al. Change in food cravings, food preferences, and appetite during a low-carbohydrate and low-fat diet. Obesity, 2011.
• Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
• Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet, 2011.
• Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss. Am J Clin Nutr, 1992.
• Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation. J Int Soc Sports Nutr, 2014.
• Jäger R, et al. ISSN position stand: protein and exercise. J Int Soc Sports Nutr, 2017.
• Wilson JM, et al. Effects of ketogenic dieting on body composition, strength, power, and hormonal profiles in resistance training men. J Strength Cond Res, 2020.
• Crosby L, et al. Ketogenic diets and chronic disease: weighing the benefits against the risks. Front Nutr, 2021.
• Cleveland Clinic. Ketosis: definition, benefits and side effects.
• US Food and Drug Administration. FDA revises labels of SGLT2 inhibitors for diabetes to include warnings about too much acid in the blood.