What Is The Optimal Carb Intake For Weight Loss?

If you find yourself needing to lose some weight you are in luck because there is a wide variety of approaches you can take. There is a lot we know about what it takes to successfully lose weight and keep it off for the long term.

The 4 Pillars of Sustainable Weight Loss

First and foremost it is going to be beneficial to eat a diet that is composed primarily of whole natural foods. The more you can minimize and eliminate processed foods from your diet the easier it will be for you to lose weight. By focusing on whole natural foods you stay more full for longer, you are far less likely to overeat, and you will be more likely to get all of the micronutrients that your body requires.

Second, we also know that trying to get the best night’s sleep you possibly can as many nights as possible is going to be important as well. The reason is that your sleep will play an important role in your desire to eat certain foods and it helps regulate hormones that will help you digest and metabolize the foods you do eat. Sleep is also important because it will give you energy for the next important component to weight loss, movement and exercise.

It is necessary to tip the caloric balance scale so that you are burning more calories than you eat in order to lose weight. You can help tip that balance more in favor of weight loss by moving your body. It is important that you move at an easy pace throughout the day. Tracking your steps is a good proxy for movement throughout the day but you don’t necessarily have to walk, you just need to move. And since we are interested in losing fat as the primary component of our weight loss efforts we also want to exercise by getting in a mix of strength training and some high intensity exercise in addition to our everyday movement.

The other component that we know is important for weight loss is community. Having a community you can lean on to support you in your weight loss efforts can be a huge predictor of success. Community is important because these are the folks you can lean on for help and support along the way. They help keep you motivated and accountable. Community could take the form of a single person like your partner, or a completely virtual group of people who all have a similar set of values and goals.

Why One-Size-Fits-All Diets Fail

While there is a lot we know about how to successfully lose and maintain weight, there is a ton more we don’t know.

A lot of what we don’t know is centered around how to eat when you want to lose weight. Our human brains crave simplicity. We would love to believe that there is just one single way of eating that everyone not only enjoys, but can adhere to in order to lose and maintain a healthy body weight.

But humans are complex.

We live in different parts of the world with different foods available.

We all have different cultures and traditions which play a large role in the types of foods we want to eat.

We all have different sensitivities and allergies which will often dictate what we eat.

We all have different foods which we “crave” and that cause us to overeat or not.

Then we have the way certain foods taste to us, people just like the taste of certain foods for no apparent reason.

This makes diet quite complex and it also makes it unlikely that we will find a single diet that helps everyone lose weight.

However there are certain approaches to dieting that can work for a lot of people in which case it is worth investigating those diets further to better understand how we can leverage them for people to lose and maintain their weight loss.

Carbohydrate Restriction Diets: From Atkins to Carnivore

One such approach to diet is carbohydrate restriction.

Diets in which carbohydrates are restricted have become quite popular over the past several years. It started off with the Atkins diet, and then moved on to Paleo and Primal, and then to Keto, and then to Carnivore. All of these diets tend to restrict carbohydrates in some form. Some are very specific around the amount of carbohydrates you can eat, while others are not.

For example, in general, a Ketogenic diet will restrict carbohydrates to 50g or less per day in order for your body to produce ketones. Paleo on the other hand says nothing about the amount of carbohydrates you can eat but instead restricts the types of foods containing carbohydrates you can eat. If it didn’t grow on a tree or come from the ground or come from an animal then you probably can’t eat it. This leaves you with carbohydrates from fruits and vegetables which are relatively low in carbohydrates compared to more processed foods.

No matter the name of the carbohydrate restricted diet they all work for weight loss because they are restricting the amount of a certain food you can eat and therefore cause most people to eat less than they would normally.

The end result…you guessed it…weight loss.

However one of the unknown questions about carbohydrate restricted diets is what amount of carbohydrate restriction yields the best results in the long term in terms of weight loss?

Can you do something like Primal and not really care about the exact amount of carbohydrates or is something like Carnivore with essentially 0 carbohydrates better?

The 2023 Meta-Analysis: 110 Trials Reveal Carb-Weight Loss Link

A recent study (Effect of Carbohydrate Restriction on Body Weight in Overweight and Obese Adults: A Systematic Review and Dose–response Meta-Analysis of 110 Randomized Controlled Trials, 2023) sought to provide an answer to what amount of carbohydrate restriction is the best in terms of weight loss.

This study was actually a meta-analysis that looked at all studies done on carbohydrate restriction on adults who were overweight or obese. To meet the inclusion criteria for this meta-analysis the studies needed to restrict carbohydrates to less than 45% of calories or less than 230 grams per day.

Key Finding: Every 10% Carb Reduction = 2.5 lbs Annual Weight Loss

After looking at all the data from these studies the researchers concluded there was a direct correlation between the amount of carbohydrates restricted and the amount of weight loss.

More specifically, for every 10% decrease in carbohydrate intake there was a 1.4 lb reduction in body weight after being on the carbohydrate restricted diet for 6 months.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10731359

After a year of being on a carbohydrate restricted diet the weight loss results were even better. For every 10% reduction in carbohydrate intake there was a 2.5 pound reduction in weight!

The researchers also split out studies in which exercise or caloric restriction was added in addition to carbohydrate restriction. As you can see from the figure above when exercise or caloric restriction were added into the mix weight loss results improved further!

This might raise some questions though, isn’t the reason why carbohydrate restriction can result in weight loss was because it reduced calories, so what does it mean to do carbohydrate restriction with caloric restriction?

The best way I can explain this is with an example.

Carbohydrate restriction alone would involve adhering to a specific carbohydrate intake. The only thing you would track when it comes to your food intake is the amount of carbohydrate you are eating. A side effect of doing this may be a caloric deficit.

Carbohydrate restriction with calorie restriction, is the same as carbohydrate restriction alone but in addition to tracking your carbohydrate intake you are also tracking your calories to make sure you actually are eating in a caloric deficit.

The fact that tracking calories along with carbohydrates results in better weight loss is likely due to the fact that participants are ensuring they are actually eating in a caloric deficit rather than just hoping the carbohydrate restriction alone will naturally keep them from eating at maintenance or in a surplus.

As a side note for some reason the researchers in this study didn’t split out results of studies for carbohydrate restriction, exercise, and caloric restriction. My gut feeling is that this would result in the best results in terms of weight loss, but we don’t know based on this study. Anyways back to the data…

So from 0-12 months, it seems like the lower your carbohydrate intake the more weight you are going to lose. However we know that many people, especially those who are overweight or obese, are going to need more than 1 year to lose enough weight to get them out of the overweight or obese category. Luckily researchers also looked at how much weight was lost and compared that to the amount of carbohydrates participants were eating in studies done for more than one year.

The Long-Term Sweet Spot: Why 30-40% Carbs Win After 1 Year

Unfortunately the nice linear association between the amount of carbohydrates eaten and the amount of weight loss starts to disappear in studies beyond a year. What the data from the studies showed was that in weight loss interventions greater than one year the sweet spot for carbohydrate intake for most people appears to be between 30 and 40% of calories.

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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10731359

In this figure above showing the data for studies greater than one year what you really want to pay attention to are the light gray dashed lines. These are the confidence intervals. Think of these like the extremes of both ends of the spectrum, these are the outliers that don’t fall in the norm. As you can see once you start to get lower than 30% of calories from carbohydrate these 2 dashed lines start to diverge more and more from each other.

The top line actually is starting to trend towards weight gain! But then the bottom line is trending towards even greater weight loss, close to 24 pounds of weight loss at a carbohydrate intake of 10% of total calories!

Remember these are the outliers though which means the weight loss numbers start to become less and less confident the further these two lines diverge from each other. So for MOST people they will see the most consistent weight loss beyond 1 year at a carbohydrate intake of somewhere between 30 and 40% of calories. To make those numbers more concrete, if you are eating 2000 calories 30% of that would be 150 grams of carbohydrates, 40% of that would be 200 grams of carbohydrates.

The Keto Paradox: Short-Term Success vs Long-Term Sustainability

These carbohydrate intakes are far off from something like a Ketogenic diet, but therein lies the problem people have with most diets.

They work great in the beginning but people can’t maintain them for the long term.

I am not saying that a Ketogenic diet or any diet that restricts carbs to less than 150 grams a day is not maintainable for everyone, I am just saying that for the average person it might be harder to maintain that low of a carbohydrate intake for that period of time.

Of course there are plenty of people who have eaten far fewer carbohydrates for far longer, lost a lot of weight and have kept it off for years.

And like I said above this is not unique to diets which restrict carbohydrate intake in order to lose weight, the trend in adherence goes down the longer the duration you look over regardless of the diet you use.

So what can we glean from this study on the optimal amount of carbohydrate intake in carbohydrate restricted diets?

It is clear that carbohydrate restriction on its own with or without tracking calories or doing exercise is an effective way to lose weight.

However I would recommend that you include exercise along with your carbohydrate restricted diet (or any diet that results in weight loss) because you are likely losing more muscle mass than if you were exercising. The lack of exercise alongside carbohydrate restriction will likely result in you not actually changing your body composition at all or ending up being lighter but having a worse body composition!

In other words you could make yourself less healthy by restricting carbohydrates and losing weight without also doing exercise.

This study also suggests that if you want to also track calories as well as your carbohydrate intake you would likely lose a bit more weight and in my opinion is a worthwhile addition to your diet practice. But if you dislike tracking and the less you have to track the better, you can be just as successful just tracking carbohydrate intake.

But what about the optimal carbohydrate intake? What amount of carbs should you eat?

That is the $1 million question!

In the short term you would likely see a significant amount of weight loss by eating something like a Ketogenic diet and restricting carbohydrates to around 50g. However don’t be surprised if this becomes hard to maintain over the long term.

Practical Strategy: Cyclical Carb Cycling for Lasting Results

What I would suggest is that you spend a few week’s lowering your carbohydrate intake down to the 50g range. Then spend several week’s at 50g assessing how hard that is for you to maintain. If you find it too restrictive and you start having cravings for things like fruit or potatoes (not potato chips, I am talking about craving baked potatoes), then it might be time to add a bit more carbohydrates back into your diet.

Try titrating up to 100-150g and spend a few week’s at that amount of carbs. Then you can drop back down again for a few week’s until you feel the cravings come back. I would just repeat that cycle for as long as you can.

My thought with this approach is that it will be much more sustainable over the long term, and will give you a bit more freedom mentally and socially to enjoy yourself. At the same time it will still provide the weight loss results you are looking for by restricting carbohydrate intake.

While I am a fan of whole food carbohydrates I also don’t deny that restricting carbohydrates can be an effective way to lose weight for many people. Many people essentially need to have some level of carbohydrate restriction in order to avoid overeating and in order to avoid eating processed foods.

Long term though I find most people tend to be able to be healthy and maintain a healthy body weight eating some amount of carbohydrate. The 150g-200g a day range seems to be a nice sweet spot for someone who is not overweight or obese and is active. That said it might take some time for someone who is overweight or obese to get to that point in which case using a carbohydrate restricted diet can be a great tool and spending time eating 50-100g of carbohydrates might be what is needed for many people to reach a healthy body weight.

Beyond Carbs: The Non-Negotiables for Body Composition

Regardless of the exact amount of carbohydrate you should eat, you need to be willing to experiment and spend some time finding the diet that works best for your goals. While carbohydrate restriction is one viable approach it’s not the only approach and it certainly can’t claim the best approach. The best approach is eating a diet of mostly whole natural foods, getting the best night of sleep you can each and every night, and getting plenty of low level movement and exercise.

From there you just need to experiment to find the specifics. If you need help with the specifics, I encourage you to sign up for my newsletter using the form below and I will email you actionable steps you can take to help find what works best for you!

References

Effect of carbohydrate restriction on body weight in overweight and obese adults: a systematic review and dose–response meta-analysis of 110 randomized controlled trials. (2023, December 6). NCBI. Retrieved April 1, 2024, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10731359/