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Do Low Carb Diets Burn Fat?
Everything You Should Know

Isaac Robertson
Published by Isaac Robertson
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: August 12, 2021

For the past decades, people have been told that the answer to all their weight loss wishes lies in low-fat diets.

You just need to cut out the saturated fat, and your health will improve, right?

But according to the recommendations from dietitians and nutritionists and my own experience with clients, carbohydrate intake is possibly the better way to attack stored body fat.

To help you understand how low-carb diets might be your best solution, we teamed up with a dietitian to come up with this guide about the recommended carb intake.

Is Low Carb Dieting The Solution To Lose Weight?

A low carb breakfast on a plain yellow background

Let me first give you a quick idea of what the human body has evolved to do.

Before food became abundant, we had to eat as many carbs from starchy foods like fruit and starchy vegetables as we could get during the summer and autumn months.

That would fatten us up for the leaner winter months, where we would switch to low-carb diets that relied on fish and meat.

But when you constantly have carbs available, your body will store as much of it as possible. And when those lean months don’t come, you end up with consistent weight gain.

Here’s what low-carb diets do from a very high-level point of view.

Impact On Blood Sugar

Restricting carbs reduces blood glucose spikes, and that stabilizes insulin levels.

As a result, there’s less excess energy that the body wants to transform into fat, and low-carb eating sends a signal that the easy energy sources are gone.

Metabolic Changes

Once you step away from a high-carb diet for a couple of weeks, your metabolism will maintain a naturally lower blood sugar level, replacing some of the “lost” energy with ketones from fat.

The ultimate form of this restrictive diet is Keto, and we’ll have some more info on it shortly.

What Should Your Daily Carb Limit Be?

A top view of a low carb diet meal

It will heavily depend on your current body composition and your overall weight loss goals.

But there are a few ranges that you can use to gradually find out how to restrict calories and carbs at the same time.

100 To 150 Grams (Of Carbs)

This would be at the upper range for low-carb diets and is often a good entry point for an initial phase. It probably won't do a huge amount for weight loss unless you reduce your daily calories a lot.

What it’s ideal for is to keep the lost weight off and maintain the health benefits of having removed a few love handles.

50 to 100 Grams (Of Carbs)

Now you’re getting into the range for low-carb diets like the Mediterranean diet and Keto diet. However, you won’t quite be at the net carbs level required to achieve ketosis.

It is a good range to give you the health benefits of weight loss without going to extreme dietary guidelines that cut out practically all sources and replace them with high-fat and high-protein foods.

20 to 50 Grams (Of Carbs)

This is where popular low-carb diets like ketogenic diets come in. When you consume fewer calories from carbs, i.e., fewer than 200 calories, then you force your body into what’s called ketosis.

It’s a natural process and the core part of the ketogenic diet, and when you stick with a calorie deficit, it may trigger some drastic weight loss.

Do All Low-Carb Diets Trigger Ketosis?

No, to get into a state of ketosis, low-carb dieters have to consume less than 50 grams of carbs per day for about a week.

That’s what the ketogenic diet aims to achieve by mainly eating low-carb food and increasing healthy fatty foods.

It is at the extremely low end of low-carb diets and has been shown to help with many health issues like weight loss, high blood pressure, and heart disease [1].

Different Types Of Carbs

A homemade citrus salad

Now, I have to complicate things just a bit more. It’s not enough to just avoid high-carb foods.

You also need to check which category the few carbs you eat fall into.

Even with a very limited carb exposure, you could be making a simple mistake. And it all comes down to the fact that there are different types of carbs.

Simple Carbs

You will generally find simple carbs in highly processed foods. But you don’t even need to reach for a candy bar to start piling on the simple carbs.

White bread and other refined carbs, like most breakfast cereals, have carbs that have been milled and crushed and broken down into a size that makes it way too easy to absorb.

So, even if you keep to less than 100 grams of carbs, make sure they don’t come from white bread.

Complex Carbs

These are the ones a weight loss diet like keto will recommend, and they come from raw fruit and vegetables as well as whole grains.

Other typical foods would be root vegetables like sweet potato, beans, legumes, lentils, and brown bread made with whole grains.

Getting more calories from complex rather than simple carbs may also be a way to deal with metabolic syndrome and type 2 diabetes [2].

Reasons A Low-Carbohydrate Diet Isn’t Working For You

Woman resting in between her dumb bell exercise

Our dietitian also pointed out that there were a few reasons why some people fail on low-carb diets while other people lose weight quickly.

And most of the time, it comes down to other lifestyle factors than the healthy low-carb diet itself.

1. Lack Of Exercise

If you’ve followed my blog posts over the years, you’ll have seen me point out that diet is 70% of weight loss. But that doesn’t mean you can completely ignore exercise, even on a low-carb diet.

Try to fit in three to four 40 minute aerobic exercises a week and limit your daily calories to see how your body’s cells react.

2. Too Many Simple Carbs

We pointed out above that simple carbs are the enemy of weight loss, even on a low-carb diet.

Use an app like Noom to find the healthiest, best low-carb foods and even introduce more animal protein. Unlike protein, carbs absorb very quickly and can replenish fat storage even while you diet.

3. Calorie Surplus

To lose weight on a low-carb diet, you have to get to a negative calorie intake.

One way to do that is by doing some intermittent fasting to gradually increase the time between your last meal of the day and the next day’s breakfast.

4. Sleep Disruption

Your body needs sleep to function properly, and if you have a bad sleep pattern, you could struggle to lose weight, even on a low-carb diet.

While it’s high-carb diets that tend to cause more sleep issues, you should still aim to build a sleep pattern and make sure you get 8 hours of sleep [3].

5. Lack Of Vital Nutrients

Switching to a low-carb diet can quickly result in you eliminating important types of food. And without all the vitamins and minerals your body needs, you could struggle with weight loss.

To help you lose weight more efficiently, make sure you don’t have any micronutrient deficiencies by getting a blood test from your doctor.

6. High Levels Of Stress

Finally, whether you’re on a low-carb diet or high-fat diet, increased levels of consistent stress will pile on body weight.

Eliminate stress and see what happens to your body.

Tips For Staying Low-Carb

A person slicing a fresh vegetable

Losing weight with a low-carbohydrate approach isn’t rocket science, but the lower you go, the more your metabolism will have to change.

If you're going to head for ketosis, then plan for the transition and keto flu, where you’ll feel down and tired for a few days.

Also, make sure you carefully track what you eat with a nutrition journaling app like Noom or MyFitnessPal.

You have to make sure that you replace carbs with healthy fats and avoid trans fats that may cause heart disease.

What Are The Disadvantages Of A Low Carb Diet?

Healthy traditional Russian salad low carb diet

Low-carb diets may eliminate a lot of foods that normally deliver a lot of healthy and important nutrients.

So you have to be careful to track what foods you cut out to see if you need to make up for those in some way.

It’s also easy to focus more on carbs and less on total calorie intake.

If your plan is to lose some love handles, then track all your nutrient intake to get a total for each day.

FAQs

Is Low-Carb Necessary for Fat Loss?

No, low-carb isn’t necessary for fat loss, but most people will find this kind of diet easier.

When you reduce the easy sources of blood sugar spikes, your body will much more naturally adjust to burning fat.

Are 100 Grams of Carbs a Day Low-Carb?

Yes, 100 grams of carbs or less would be considered low-carb. However, it would take 50 grams or less per day to get your body into ketosis for maximum fat reduction effect.

How Long Does It Take To Start Burning Fat on a Low-Carb Diet?

It can take as little as a few days to start burning fat on a low-carbohydrate diet. Some initial effects will be from losing water weight, but it will help you lose weight effectively if you stick with this approach.

Are You Going to Try a Low Carb Diet?

If you find that low-fat diets have failed you to achieve your ideal body weight, switching to a lower daily carb intake might be the best solution to help you lose weight.

It’s a kind of diet that will take some adjusting, and you should consider using an app to help you with your carb tracking.

But once you get into it, you should notice the pounds fall off.


References:

  1. https://healthblog.uofmhealth.org/keto-diet-and-heart-health-perfcon
  2. https://www.sciencedirect.com/science/article/abs/pii/S0939475319303412
  3. https://www.today.com/health/sleep-doctor-michael-breus-knows-your-sleep-type-when-you-t136572

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