Why a Low-Carb Diet Is Best for Weight Loss

If you want to lose weight, you have a number of choices. The most popular is to cut calories and eat a low-fat diet. A way that’s becoming more popular, because it works much better, is to cut carbohydrates. Here we’ll take a look at scientific proof that a low-carb diet is best for weight loss.

No calorie counting

The biggest impediment to losing weight on a low-calorie diet is hunger. If you voluntarily reduce calories while eating the same foods, you get hungry, as is to be expected. Your body defends its weight, i.e. it has a set point, and makes you hungry if your weight moves away from the set point.

On a low-carbohydrate diet, you merely cut the amount of carbohydrates in the diet, and in most studies looking at low-carb diets, the dieters ate as much as they wanted. Only carbohydrates were restricted. Cutting carbohydrates lowers levels of the hormone insulin, which signals the body to store fat, and which is responsible for setting the body weight set point. The result is nearly effortless weight loss.

In the first study we’ll look at, a group of obese women were randomized to either a low-fat, low-calorie diet, or a low-carbohydrate diet that was not restricted in calories, and followed for 6 months. Weight loss result in the chart below.

low carb weight loss

The low-carb group ate 20 g of carbohydrate daily, but were allowed to increase this to 40 to 60 g after 2 weeks, so long as they remained in ketosis as shown by urinary testing. The low-fat group was restricted in calories by 30% and ate about 55% of their calories as carbohydrates.

Despite the fact that the low-carb group could eat as much as they wanted, they spontaneously reduced their calorie intake to about the same as the low-fat group. That shows the power of low-carb in reducing hunger and changing the body’s weight set point. And they still lost more weight, an average of 7.6 kg, than the low-fat group, at an average of 4.2 kg.

You can even eat more calories and still lose weight

The second study concerns weight loss in obese teenagers. A group of adolescents, average age 14, were assigned to either a low-carb diet or a low-fat diet.

The low-carb group was instructed to keep carbohydrates at less than 20 g a day for the first 2 weeks, but increasing to 40 g a day in weeks 3 through 12. They could eat as musch as they wanted.

The low-fat group was instructed to keep fat at <40 g a day. They also could eat as much as they wanted.

Here are the results.

low carb weight loss 2

The low-carb teenagers averaged 9.9 kg of weight loss, compared to 4.9 kg in the low fat group. (That’s 22 pounds vs 11 pounds.) That was despite the fact that the low-carb group ate over 1800 calories a day, while the low-fat group ate 1100 calories a day. That’s the power of lowering carbohydrate intake. Also it’s guaranteed that the low-carb group was less hungry.

You don’t even need to reduce carbohydrates much

The third study compared a low-carbohydrate to a low-fat diet in severe obesity. These people had a high prevalence diabetes or metabolic syndrome.

The low-carbohydrate group was instructed to keep carbs at <30 g a day. However, they didn’t. They could eat as much as they wanted.

The low-fat group was instructed to keep fat  at <30% of calories, and to reduce their calorie intake by 30%.

low carb weight loss 3

The low-carb group lost 5.8 kg after 6 months, the low-fat group 1.9 kg. (13 pounds vs 4 pounds.) The low-carb group spontaneously reduced their calorie intake, so that the 2 groups ate about the same number of calories, again showing the power of reducing hunger and body weight set point.

Notably, the low-carb group wasn’t very compliant, and they only reduced their carb intake to 37% of calories at 6 months, vs 51% for the low-fat group. Yet they still lost more weight.

Low-carb vs low fat and Mediterranean diets

The fourth study was a three-way comparison between a low-carb, low-fat, and Mediterranean diets. The low-fat and Mediterranean diets were restricted in calories, with limits of 1500 calories daily for women, and 1800 for men.

The low-carb dieters could eat as much as they wanted, so long as they restricted carbohydrates to 20 grams daily initially, but increasing to a maximum of 120 grams.

Here’s what happened:

low carb weight loss 4

Once again, low-carb is a clear winner. Low-fat lost 2.9 kg, Mediterranean 4.4 kg, and low-carb 4.7 kg. The low-carb group still ate a whopping 40% of calories as carbohydrates, although that was down from 51% at baseline, representing a drop of 120 grams of carbs daily.

Noteworthy is the increase in weight after the first few months of weight loss, which was greatest in the low-carb group. That group actually increased its carb intake slightly. Another explanation might be a lower metabolic rate and/or less exercise. the low-carb group did decrease the amount of exercise between 6 and 24 months; the low-fat group increased exercise.

Reviews of low-carb diets

We’ve seen above that several studies have found that low-carbohydrate diets are superior for weight loss. have I cherry-picked the studies? Nope.

Several meta-analyses (reviews of studies) have found that low-carb diets beat calorie-restricted low-fat diets.

Dietary Intervention for Overweight and Obese Adults: Comparison of Low-Carbohydrate and Low-Fat Diets. A Meta-Analysis. This study concluded:

This trial-level meta-analysis of randomized controlled trials comparing LoCHO diets with LoFAT diets in strictly adherent populations demonstrates that each diet was associated with significant weight loss and reduction in predicted risk of ASCVD events. However, LoCHO diet was associated with modest but significantly greater improvements in weight loss and predicted ASCVD risk in studies from 8 weeks to 24 months in duration. These results suggest that future evaluations of dietary guidelines should consider low carbohydrate diets as effective and safe intervention for weight management in the overweight and obese, although long-term effects require further investigation.

Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. This study concluded:

Compared with participants on LF diets, participants on LC diets experienced a greater reduction in body weight.

What to eat on a low-carb diet

Low-carb diets vary in the degree of carbohydrate restriction. One scheme that I used in my book Stop the Clock was the following:

  • moderately low-carb: <130 grams of carbohydrate daily
  • low-carb: 50 to <130 grams daily
  • very low-carb ketogenic: <50 grams daily.

As we saw in this article, virtually any degree of carbohydrate restriction is beneficial. But, the more you restrict carbs, the better your weight loss is likely to be.

Timothy Noakes, M.D., a noted advocate of low-carb diets, recently published an article, Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review. In it, he listed the following foods as being “green-lighted” for a low-carbohydrate diet:

low-carb-food-list

This list is meant for people who are insulin-resistant. If trying to lose weight, it would be a good idea to go easy on the added oils and nuts.

You should omit the following foods entirely:

  • anything made with flour: bread, pasta, tortillas, pastries
  • anything with added sugar: soft drinks, fruit juice, candy, cookies
  • starch: potatoes, sweet potatoes

Did I miss anything? It’s easy, just eat plenty of meat, eggs, vegetables, cheese. Don’t go hungry.

For what it’s worth, I eat this way all the time. Most days my carb intake is probably 20 to 60 grams, some days rising to 100.

PS: Check out my books, Dumping Iron, Muscle Up, and Stop the Clock. And don’t forget Top Ten Reasons We’re Fat.

PPS: You can support this site by purchasing through my Supplements Buying Guide for Men.

Leave a Comment:

26 comments
Belovar says January 16, 2017

Something I have been thinking about is what effects a ketogenic combined with 100% caloric intake would have. Any thoughts on this?

Reply
    P. D. Mangan says January 16, 2017

    There are health benefits to it, and could even cause fat loss.

    Reply
Retardo the NotanymoreCarbsabsorber says January 16, 2017

Ten years ago in my school+uni phase I ate often at McDonalds.
I indulged, and ate 5 to 10 items, sometimes binge-eating with pals playing video
or watching movies.
Today I calculated how much sugar I often ate in less than 30 minutes:
around (horrible) 500 grams of sugar in one “meal”.
Dammit. No wonder I was fat. And an uneducated idiot for eating like this.

If you want to try, check for yourself, the EU/German website has nutritional data for
their products right here:
http://www.mcdonalds.de/produkte/alle-produkte

Not that I want to single out a company, practically the whole food industry packs
their products with sugar, often cleverly hidden. (Even the McNuggets are sugar
bombs, which one might not expect from what seems little more than chicken meat).

And I know why they are doing it, this sugar stuff is quite addictive, I experienced it myself.
After I ate low-carb, not only my body weight lowered towards a healthy one, but I also got
more active, had more energy, no more “ups and downs” in the day and generally better health,
indicated by blood tests and how my skin looked.
Sadly, trying to make my family adopt a LCHF diet was met with much aggression;
they still eat around 300g+ of sugar every day.

Reply
jjsst95 says January 16, 2017

Hey PD,
Off topic…
I have found your website very useful and take many of the supplements on your supplement guide and try to following a low carb diet with some intermittent fasting in the mix as well as strength training. My new wife and I are trying to conceive but my sperm quality and quantity is sub-optimal. I used to be on TRT but my urologist has instructed me to stop, although he wasn’t very much help beyond recommending an interventional procedure such as intra-uterine insemination. Is there anything in particular that you have come across, beyond your current recommendations, that may promote male fertility?
Much appreciated.

Reply
jjsst95 says January 16, 2017

Thank you!

Reply
Why a Low-Carb Diet Is Best for Weight Loss says January 16, 2017

[…] post Why a Low-Carb Diet Is Best for Weight Loss appeared first on Rogue Health and […]

Reply
Thomas says January 16, 2017

Hi Dennis, I hate to keep being particular about this, but I want to make sure I get it right. Is there any kind of dairy that we SHOULDN’T eat (or drink), or is dairy as a rule okay? Thanks very much.

Reply
    P. D. Mangan says January 16, 2017

    Hi Thomas – don’t drink milk. Fermented dairy of any kind, such as yogurt, cheese, kefir, or other dairy such as butter and cream, is great.

    Reply
      Thomas says January 16, 2017

      Excellent, thanks so much.

      Reply
      MarkB says January 21, 2017

      Hi PD,

      could you summarise or link to the reasons for not drinking milk? I consume milk and yoghurt, but I could give up milk if I was convinced. Thanks.

      Reply
        P. D. Mangan says January 21, 2017

        Hi Mark – it appears that the lactose (milk sugar) in milk may be the guilty party. Fermented milk products, like yogurt or cheese, have little to no lactose due to fermentation. Milk is about the only thing that reliably make my face break out. So basically we’re back to sugar. I dson’t know of any research specifically examining milk vs say yogurt on any of these angles.

        Reply
          MarkB says February 9, 2017

          Very belatedy,

          Thanks for that info on milk. I think I will give it up. I have read material that promotes the superiority of raw (i.e. not pasteurised or homogenised) milk, but it is expensive and inconvenient to buy it in the UK.

          Reply
Marcello says January 20, 2017

I see that on low-carb my muscles tend to shrink.
Any solution?

Reply
    P. D. Mangan says January 20, 2017

    I assume you lift. Make sure you get enough protein, and add a few carbs if necessary. Low-carb doesn’t have to be ketogenic. Some days I may eat 100 g carbs, other days next to zero.

    Reply
30 Days To Greatness - Honor and Daring says January 22, 2017

[…] A low-carb diet has proven to be the best diet for weight loss and I could stand to lose about 20 pounds. A strict Paleo diet that stays low carb is guaranteed to […]

Reply
Right Stuff says January 23, 2017

Anecdote here. I reduce carbs, cut bread & starch to almost nothing. Carbs from veggies. Lift heavy (as always) and based on mirror check) and max lifts. (I usually do a max weight double every time before moving on to 90-80% intensity work) and I’ve gained strength and lost fat.

Contrast this with years of post workout pizza, pasta, and all manner of ‘man food’ and I am doing better with salad and salmon and EVOO.

In fact, every time I eat starch vasculatity goes down and – contrary to typical broscience, those huge carb laden meals do little if nothing in the performance or appearance department.

Is there something about the release of excess insulin response (carb heavy meal) itself that inhibits muscle growth? This seems to be the case with me, but would be contrary to accepted excercise science.

Reply
    P. D. Mangan says January 24, 2017

    Interesting. No, there’s nothing I know of about insulin that would *inhibit* muscle growth. Possibly you weren’t getting enough protein at the time? (Only thing I can think of.) Another possibility is what you noted: your vascularity went down, indicating some extra sub-q fat. That, insulin will do.

    And BTW (not that you asked, but to reiterate to others), protein raises insulin all that’s necessary for muscle growth. Adding extra carbs to a protein meal after workouts doesn’t stimulate muscle growth more than with protein alone.

    Reply
      Nick says January 24, 2017

      Maybe fat in the post-workout feedings was slowing digestion and uptake of much-needed protein?

      Reply
Nick says January 24, 2017

Interesting and useful as usual. Got me thinking, it did. Last February, I started tracking my weight and “macronutrient” consumption with a little program I wrote. But I never thought of graphing my weight, as weight loss itself has not been an explicit goal of mine. Until a month ago, that is, when it occurred to me to chart it.

Mid-May, I went starch-free, if not low-carb or very-low-carb. Guess what the chart shows. Aye, that’s exactly when my weight drop took a significant turn upwards. And so I thought I’d compare it to the chart you have above comparing obese women on low-fat and very-low-carb diets. I slapped together this chart overlaying mine on the other two:
http://i64.tinypic.com/30lflnp.jpg (Please copy and make it visible here if you want.)

It shows that the first 11 weeks of my going starch-free mimic the low-fat dieters more than the very-low-carb ones, but then my weight loss at 24 weeks is somewhat closer to the v-l-c dieters. But there are a few caveats here.

1.) I have not been restricting myself to v-l-c grams of carb intake per day, though I do avoid starch & sugar as much as possible. 2.) I drink beer every evening, sometimes a fair bit. 3.) I’ve been putting on muscle to counter fat loss, but since I’ve not been tracking body fat composition, I have no idea how much. 4.) I was nowhere near as obese as these women apparently were, with my starting weight at 84.5 kg (5’10”), ending about 76.5. (I’m now below 76, FWIW, where I’ve been hovering since about mid-November.)

I also switched over to HI weight lifting a couple of weeks after going starch-free, and started really focussing on intensity a couple of months later. Point being, I believe I’ve put on significant kgs of muscle during this period of weight loss.

Anyway, just more anecdotal data. And the dotted line bit is where I was travelling and neither weighing myself, nor working out for a couple of weeks, but still eating as well as possible, although drinking lots and lots.

And since I started doing intermittent fasting a couple times a week (18-21 hours), the day-to-day fluctuations have dropped a bit, which may be interesting.

Reply
Gail says January 26, 2017

Hello, I am wondering if you *ever* eat fruits like apples, pears, etc.? I’m guessing you eat berries from time to time? Sorry if you’ve talked about this in the past, I’m new to your website and haven’t read through all of your posts 😊

Reply
    P. D. Mangan says January 26, 2017

    Hi Gail – yes, I do. Not much, but some, an apple here and there, that sort of thing. I eat berries more: blueberries, raspberries. Also chocolate, which obviously not a fruit, but has sugar.

    Reply
      Nick says January 27, 2017

      Had my first apple in ages yesterday. It didn’t seem sweet (I think you said somewhere they taste like candy to you now), but it was also a variety that’s smaller & more sour than the standard Washington (state!) supermarket varieties: a Pinova.

      I also just eat berries for fruit these days, on my post-training-day breakfast of yogurt/quark/seeds, or when I have that as a training-day dessert. No more mangos, though I do love them. Kiwis are OK though, not so sweet.

      Reply
The Simplest Health Plan: Cut Carbs, Lift Weights - Rogue Health and Fitness says January 29, 2017

[…] fitness expert who’s more than skeptical about low-carbohydrate eating. Despite the fact that low-carb diets outperform low-fat, calorie-restricted diets every time they’re put to the test, Schoenfeld thinks the evidence is lacking. Because diets are not matched for calories and protein. […]

Reply
Terrence says April 10, 2017

Hi Denis, I’m attempting low carb for the second time and again I’ve had a rash break out on my chest. It’s clear restricted carbs cause the issue as one reintroduced the rash subsides. Have you heard of others experiencing this and do you have any advice on which are the least worst to eat?

Thanks,

T

Reply
    P. D. Mangan says April 11, 2017

    Hi Terrence: that’s an odd one. Normally I’d think it would be the other way around and some plant allergen or chemical would be doing that, and it’s possible that it is, only the low-carb is allowing it. IOW, removing carbs (or anything) from what you used to eat shouldn’t result in unusual symptoms like a rash. Nevertheless, if you want to eat carbs, sweet potatoes are usually considered the most benign; also of course all kinds of vegetables that are not very low carb, like onions or carrots. I used to eat a fair amount of white potatoes myself, although that’s a nightshade plant and does cause allergies in some people. If you need even more carbs, white rice is low in plant toxins.

    Reply
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