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How Long Does It Take To Lose Weight in Ketosis?

Connor Sellers
Published by Connor Sellers
Last updated: May 9, 2023

With more people wanting to drop weight quickly and efficiently, keto diets are becoming more popular by the day.

Over my career as a fitness trainer, I’ve come across many folks skeptical of the efficiency of ketogenic diets because of their high-fat dietary requirements. So, I spoke to a dietician and analyzed quite a few research papers on the matter.

Combining my previous knowledge and what I learned, I’m going to explain how fast ketosis can burn away fat.

Let’s get into it.

Quick Summary

  • You will start losing weight between 2-4 days while on the ketosis diet.
  • The ketogenic diet is a high-fat, low-carb diet, and is very effective in weight management.
  • To achieve ketosis, avoid complex carbs, and sugars as much as possible.

How Fast Will I Start Losing Weight on Ketosis?

A woman eating salad

You will start losing weight within 2–4 days or longer on ketosis.

How much weight you lose will depend on various factors such as your metabolism, fitness levels, fat-protein-carb intake, total caloric intake, and how disciplined you are with the diet.

You may start to lose weight at a fast pace in the initial stages of the diet, but from what I've observed, most of it is water weight.

After around a couple of weeks, your body begins adjusting to the keto diet, and your weight loss slows down.

Try not to lose over 2 pounds of weight per week. That’s because rapidly shedding fat can lead to dehydration, mood swings, irritability, and weakness [1].

Related: Do You Have to Be In Ketosis to Lose Weight?

How Ketosis Burns Body Fat and How to Get Into It

A person holding a salad

Ketosis is a state in which you burn body fat to make free-fatty acids that can be used in muscles, and it also makes ketones which are used by the brain and some other tissues.

During ketosis, your body doesn’t have enough sugars to use for energy (because you don't consume them for the diet).

So, it resorts to burning body fat as a source of energy, leading to fast weight loss.

You enter ketosis by first upping your protein and fat intake. At the same time, you have to almost completely restrict carbs.

After a couple of days, your body won't have any carbs (its preferred source of energy) to produce energy. So, it turns to fat for energy. Your liver then breaks down dietary fat [2].

The oxidation of these fatty acids leads to the production of the aforementioned free-fatty acids and ketones, which your body uses as fuel for lean muscle building and metabolism.

“A ketogenic diet has been shown to improve blood sugar control for patients with type 2 diabetes, at least in the short-term.”

- Dr. Saurabh Sethi, MD, MPH, Gastroenterologist

Factors That Affect the Rate of Fat Loss

Several factors affect the level of fat mass you lose on a keto diet.

Here are a few of the common ones:

  • Too many carbs: You might be consuming more carbs than you think. Keep away from major carb sources like bread, rice, and oats. Stick to vegetables.
  • Poor diet plan: Your diet plan might not contain wholesome sources of healthy fats and proteins. Make sure you eat a balanced diet that contains quality sources of these nutrients.
  • Overeating: You may be eating keto-friendly foods, but you might not be on a calorie deficit. Count your calories carefully so you lose weight efficiently.
  • Lack of sleep: Studies show that lack of sleep can negatively impact your weight loss [3]. Aim for 7–9 hours of quality sleep to help boost your metabolism.
  • Undiagnosed medical condition: If you’re doing everything right and still not losing fat, you may have a medical condition. We recommend visiting your physician to see what you can do to shed fat.

Related Articles:

Can Supplements Speed Up Weight Loss?

A fit woman holding a salad bowl

Yes, supplements can speed up your fat loss when in ketosis.

In my experience with clients who went on the keto diet to lose weight, taking fat burners sped up their weight loss.

Although no evidence suggests fat burner supplements sped up the rate of ketosis, they helped my clients in the following ways:

  • It decreased their appetite, leading them to consume fewer calories and avoid carb intake and processed foods.
  • It gave them more energy that fuelled their workout sessions for weight loss compared to clients who didn’t take them.
  • Clients on the keto diet who took fat burners lose fat above the average weight loss rate of those who went keto without fat burners.


How Do I Know My Body Is Burning Fat on the Ketogenic Diet?

You know your body is burning fat on the ketogenic diet when the ketone levels in your blood are between 0.5-3 mg/dL.

Certain levels of ketones in your urine, blood, and breath strongly indicate that you're losing weight.

Can I Maintain Weight Loss After Going Off the Keto Diet?

Yes, you can maintain your weight loss after going off the keto diet. To do so, you must make healthy food choices, reduce calorie intake, and exercise regularly.

What Should I Avoid to Achieve Ketosis?

To achieve ketosis, you should avoid foods with sugars and complex carbs as much as possible.

Some of your food will contain small amounts of carbs, but you can still achieve ketosis by keeping your sugar and overall carb intake to a minimum.

Final Thoughts on Ketosis and Fat Loss

Achieving ketosis might be one of the best options to lose weight, but it’s not the most convenient option because it requires a lot of prep work and time. And some people might not find a high-fat diet too appealing.

Luckily, there are easier ways to lose weight, such as taking natural fat burners:

These products that we tested for safety and efficacy ourselves can help you burn body fat, maintain muscle, reduce fat storage, and boost energy levels.


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