Zero carb weight loss: muscle, fat or water?

A common concern amongst beginner ZCers – and also a sneer at them from the plantatarians – is that the weight lost on a zero-carb/LCHF way of eating is mainly water and muscle.

The continued existence of this myth – which I could easily have devoted a ‘Vegan Pork Pie’ to – is down to the ‘victory of dogma over data‘ as Messrs Volek and Phinney put it. For example, a scientist may design a study to run for two weeks, knowing full well that if it ran for, say, six weeks the results would not look the way they wanted them to look. Or a scientist may choose not to publish ’embarrassing data’, fairly safe in the knowledge that for the most part peer-reviewers won’t go the extra mile and join the dots.

So bad science can turn into misinformation that in turn becomes woven into the fabric of our understanding of nutrition. Threads such as the evils of saturated fat, the dangers of red meat, the necessity to consume fibre… we all seem to have absorbed information – or misinformation – in all these areas.

This ‘muscle and water’ myth comes from, as Volek and Phinney say, a 1976 study on composition of weight loss, a study that has been cited well over 100 times in peer-reviewed literature in order to reference and promote the study’s conclusions, which were that most of the weight lost on a LCHF diet is water and lean tissue and hence LCHF is a disaster for healthy weight loss. First, the difference in lean tissue lost by the subjects, which was over a mere 10-day period, itself a red flag for the validity of a nutrition study, was not statistically significant, yet the authors incorrectly claimed that there was more lean tissue loss on LCHF. Second, the subjects were given very low amounts of sodium each day, when it was known that starvation or severe carb restriction accelerates sodium excretion, resulting in heavy water loss.

A similar, but much better designed study a few years later gave its subjects 5g of sodium per day, and found no difference in water weight loss between LCHF and moderate carb, low fat groups. Not only that but the low-carb diet gave better preservation of lean tissue than than the higher carb diet. This study was carried out over 6-8 weeks, not 10 days, to add to its sensible, real-world approach, and despite this it has not been cited as often as the earlier study.

So that’s one reason why so much of our early weight loss is ‘water weight’: many people don’t take in enough sodium as they cut the carbs. Every gram of glycogen – the fuel derived from dietary carbohydrate – has to be stored in the body with a about two grams of water. We can store around 500g of glycogen, plus 2g of water/g carbs = 1500g in glycogen and water, or 1.5kg of potential weight fluctuation (more if you are a well-trained, high-carbing athlete). Fat cells, on the other hand, are stored with minimal water. As you become fat-adapted, then, and maintain good levels of sodium, your water weight fluctuation should be less.

So to sum up: when you ditch the carbs, only the first load of weight loss will include water – thereafter it’s fat (and most likely no lean tissue). Before you are fat-adapted, and in a low-sodium environment, you will shed water. But you will be shedding fat, too. So if you lose 5kg in weight in the the first 4 weeks of changing your diet, say, it’s likely that early on a lot of that was water, probably around 2.5kg, and hence 2.5kg fat. A week later and you’ve lost a total of 6kg, say, well now you’ve shed 3.5kg of fat. And if you stay with it for 20 more weeks and lose 0.5kg per week, all of those subsequent 10kg will be body fat and none of it will be muscle or water.

As with everything ZC-related, persistence and patience are key. And, just as important, be prepared to question where those voices saying ‘Eat veg, eat fibre, eat Olivio’ come from, and where the information comes from. If it’s anti-zero-carb, then it most likely was plucked from the scientist’s backside. One of the aims of this blog is to help you overcome these voices, so shout if you think I might be able to help clarify something you’re unclear on.

Till next time.


5 thoughts on “Zero carb weight loss: muscle, fat or water?

  1. badgerdaddy June 25, 2018 / 12:58 pm

    I’ve got about a billion questions, not least because my adventure in triathlon begins this very weekend.
    Where does white meat fit into this, if at all? What does a zero/low carb meal/meal plan look like? How long does adaptation take? etc etc etc


    • huwcoache17 June 25, 2018 / 1:15 pm

      If you email me I’ll try and answer without it being a whole book (now there’s a thought…). Do you have my email?


      • badgerdaddy June 25, 2018 / 1:17 pm

        Got your wordfarm one, does that still work?


      • huwcoache17 June 25, 2018 / 1:20 pm

        huw, then coach, all one word, then the ‘at’ symbol, then


  2. Michelle June 25, 2018 / 1:16 pm

    Reblogged this on UK Carnivore Club and commented:
    Another fine post from Huw. It just shows how much negative dogma is still carried forward in the world of food and nutrition and how impossibly hard it can be to shake it off.


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