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Evidence-Based Death to “Carbs Make you Fat”

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By Daniel Sobhani, CEO of Freeletics, Instagram
(For simplicity, I’ll refer to “low carb” as all diets that try to limit carbohydrate intake to less than 10% of total calorie consumption, which, for most people, is approximately 35 - 75g a day. This article is mostly directed towards low carb & losing fat - I’ll only briefly talk about endurance performance / muscle hypertrophy)

Low carb: a lot of hype, a lot of pain

It feels like common knowledge: you should cut carbs to lose weight. Keto is a big thing, and people on diets regularly sit in front of plain salads, zoodles, or watery soup. And the war between “Cut fat! Boo, cut carbs!” is forever ongoing.

A sudden, dramatic reduction in carbs often leads to people suffering. Mood swings, feeling less energetic, low pleasure in eating and practical challenges in finding the right foods. These things can all lead to binge eating, low diet adherence, and ultimately dropping out. Of course, for some people, low carb works well. But from 10 years of experience with millions of users, I can say that for the majority, it doesn’t.

Why the carb debate never ends

  • The human body is complex, with a lot of interactions we don’t fully understand. This leaves avenues open for continuous, new questions and hypotheses, as well as a desire to simplify the whole thing and give easy answers.
  • There are few people who have the required expertise to objectively weigh in on this topic. Everyone eats, and therefore everyone believes they have a valid opinion. It is also extremely difficult, even for professionals, to evaluate the quality of scientific information and arguments that are put forth.
  • There are many charlatans out therewho have financial or ideological reasons to propagate a new, simple, or even “magic” way to be healthy and get your dream body.
  • Carbs are (unfairly) lumped into one group. There is a massive difference between consuming a pizza (carbs!) or oven-baked veggies with sweet potato (also carbs!). The first is highly refined, highly palatable and much more likely to contribute to an overconsumption of calories - aside from all the other negative health impacts. Cutting out such highly refined, tasty (and therefore addictive) foods will significantly help with weight loss and improve health, but is often just called “cutting out carbs.”

Research clearly shows: a low-carb diet has no inherent benefits for weight loss

Before jumping into that topic, let’s talk about low carb for muscle growth (hypertrophy) and endurance performance. But just very briefly. Why briefly? One, because it’s not a very big topic in this area, and two, it would double the length of this article. However, to summarize:

  • There are a lot of common myths and mostly purely observational studies around hypertrophy. The one real consistent finding is that restricting carbs to ≤50g a day reduces muscle gain and / or increases the loss of lean mass during caloric restriction phases.(5)
  • For endurance training, in simple terms: eat carbs or you’ll lose out on performance.

Now, back to low carb for weight loss. The vast majority of studies that take protein and overall calorie intake into account show no significant advantage (fat loss) of low / no carb diets.(1-3) All controlled feeding studies (where food intake was controlled as closely as possible in a closed lab environment, or provided by the lab to outpatients) that I am aware of, which matched protein and calorie intake, have also not shown a fat loss benefit in the low carb section.(4)

For some, a low-carb diet still can be worth it

I’m ignoring medical conditions, but even then, low-carb diets can work well for losing fat. Many of the foods that have a high calorie density and / or lead to overeating include carbs (like the aforementioned pizza…). Cutting carbs out mostly or even completely eliminates these foods by definition.

BUT, and there are a lot of them:

  • You still need to be in a caloric deficit (your overall caloric intake must be less than your caloric expenditure - or said differently, you need to eat less than your body burns). And there are a lot of foods containing fat and protein that are very high in calories - it’s not just carbs.
  • Most people will suffer physically and psychologically if they cut carbs. That alone is a reason not to do it, as a sustainable, healthy fitness lifestyle shouldn’t and doesn’t have to mean suffering. And it significantly decreases the chance you’ll actually stick to your plan.

Practical tips & applications

  • I recommend including carbs in any diet (weight loss, muscle gain, performance). The chances are high that you’ll feel better, perform better, have more fun in life and therefore stick to your plan. That’s unless there are medical reasons not to, or you are one of those rare humans who really doesn’t like carbs.
  • Eating predominantly unprocessed foods will make it so much easier to be healthy and achieve your physical goals. As a rule of thumb: the fewer ingredients something has, the less processed it is. The less you understand the ingredients, the more processed it is. An orange is an orange - one ingredient. A steak with potatoes has two ingredients. Your microwave Mac & Cheese probably has 20+ ingredients with a lot of chemical names (so always check the label!)
  • Simple tips to help you avoid overeating: have a lean protein source with every meal, have a bowl of veggies (with a light sauce if at all, nothing creamy or pre-mixed), and don’t drink anything with calories (juice, sodas, alcohol) - unless you want to make an exception (for alcohol, dessert, etc.). Keep the exceptions to max. three per week.

Eating healthy shouldn’t be an added stress, and making carbs the enemy is sure to create an unhealthy relationship with food. Instead, focus on eating the right types of carbs while keeping an eye on your calorie balance. This is a sustainable and proven path to a healthy lifestyle.

Take your nutrition to the next level and gain the knowledge to get strong, lean, and healthy with the Freeletics Nutrition Course.

Sources

[1] Aragon AA, Schoenfeld BJ, Wildman R, Kleiner S, VanDusseldorp T, Taylor L, Earnest CP, Arciero PJ, Wilborn C, Kalman DS, Stout JR, Willoughby DS, Campbell B, Arent SM, Bannock L, Smith-Ryan AE, Antonio J. International society of sports nutrition position stand: diets and body composition. J Int Soc Sports Nutr. 2017 Jun 14;14:16. doi: 10.1186/s12970-017-0174-y. PMID: 28630601; PMCID: PMC5470183.

[2] Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JPA, Desai M, King AC. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA. 2018 Feb 20;319(7):667-679. doi: 10.1001/jama.2018.0245. Erratum in: JAMA. 2018 Apr 3;319(13):1386. Erratum in: JAMA. 2018 Apr 24;319(16):1728. PMID: 29466592; PMCID: PMC5839290.

[3] Soenen S, Bonomi AG, Lemmens SG, Scholte J, Thijssen MA, van Berkum F, Westerterp-Plantenga MS. Relatively high-protein or 'low-carb' energy-restricted diets for body weight loss and body weight maintenance? Physiol Behav. 2012 Oct 10;107(3):374-80. doi: 10.1016/j.physbeh.2012.08.004. Epub 2012 Aug 19. PMID: 22935440.

[4] Hall KD, Guo J. Obesity Energetics: Body Weight Regulation and the Effects of Diet Composition. Gastroenterology. 2017 May;152(7):1718-1727.e3. doi: 10.1053/j.gastro.2017.01.052. Epub 2017 Feb 11. PMID: 28193517; PMCID: PMC5568065.

[5] Ashtary-Larky D, Bagheri R, Asbaghi O, et al. Effects of resistance training combined with a ketogenic diet on body composition: a systematic review and meta-analysis. Crit Rev Food Sci Nutr. Feb 2021:1–16. doi:10.1080/10408398.2021.1890689