What happens if you eat 5,800 calories daily on an LCHF diet?


What happens if you “overeat” on an LCHF diet? It’s a common question and here’s one possible answer.

The young man Sam Feltham has done a three-week experiment, where he’s been eating enormous amounts of LCHF-food. On average 5794 calories daily of which “only” 10% as carbohydrates (menu).

According to over-simplified calorie counting, energy expenditure isn’t affected by what you eat. All excess calories you eat will then lead to weight gain. If this were true Feltham would have gained 16.5 lbs (7.5 kg) during the three weeks, but in reality he only gained 3.5 lbs (1.7 kg).

Here’s the explanation:

Theory and reality

There’s a difference between calculated energy surplus and real energy surplus. Apparently Feltham didn’t have a large real energy surplus, as he didn’t gain more weight.

The most likely explanation to me is that his energy expenditure increased substantially during the experiment. Maybe there are other explanations? Perhaps his body also adapted by not taking up all the nutrients he ate?

I’m not surprised by the results. If you starve long term you don’t lose as much weight as simple calorie counting predicts. The body will decrease the metabolic rate. If you overeat you don’t gain that much weight. The body adapts and tries to maintain an appropriate fat mass.

Some find it hard to believe in Felthams results and suggest that he’s lying. I don’t think so. There are several previous reports from people who have done similar experiments – stuffed themselves with copious amounts of LCHF-food. Weight gain tends to be small or non-existent, so Feltham’s results seem to be typical.


The above applies as long as the body’s hormonal regulation is balanced. Eating large amounts of bad carbohydrates may interfere with hormonal balance. Large amounts of the fat-storing hormone insulin are then produced.

So what happens when you overeat bad carbohydrates to the extreme? A good example is the movie “Supersize Me”.

Morgan Spurlock did a similar experiment: he ate 5,000 calories daily for 30 days – at McDonalds. The difference was that this was not an LCHF diet, but HCHF (high carb high fat). There were about as many “excessive” calories, but Spurlock did not only gain 3.5 lbs (1.7 kg). He gained a whopping 24.5 lbs (11.1 kg).


Professor Fredrik Nyström did a study where twelve students overate, but to a less extreme degree, “only” a few thousand extra calories daily in the form of carbohydrate-rich fast food, for four weeks. Just adding these extra calories made them gain on average 14 lbs (6.4 kg).

Paulo Roberto, Sweden, made a similar TV documentary the other year. He ate large amounts of carbohydrate-rich junk food and gained 33 lbs (15 kg) in two weeks!


There is a difference between overeating and overeating.

When eating bad carbohydrates it’s easy to gain weight quickly. You’ll get plenty of the fat-storing hormone insulin in your blood.

It’s generally hard to gain weight on an LCHF diet. It’s even difficult to eat too much food, as you then usually have to eat more than you want. Even if you force down large amounts of LCHF-food, against your will, the result is usually as it was for Feltham. It’s a constant struggle and weight gain will likely be modest.

Overweight people eating as much as they want on an LCHF diet will typically lose weight.

What do you think about the experiments?


Previously on problems with calorie counting

Better ways to lose weight

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Top comments

  1. Suzanne
    I have been on the LCHF diet for about 10 months and I have lost approximately 70 lbs. It was not easy getting started but it has became a way of life. Never did I realize how bad choices eating out could cause so much weight gain. When I splurge for the weekend it kills all the hard work from the past couple weeks. It took some time changing my mind set that I can't eat "bad" anymore. I have found that a "cheat" meal every couple weeks keeps me focused and reboots my metabolism. However, I am now wanting to do this less and less. Good luck to anyone trying the LCHF diet. It does pay off in the end!
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  2. FrankG
    Not only did he not gain the "weight" as predicted by CICO but his waist measurement decreased by 3cm during these 21 days!

    An interesting and enlightening experiment but none of which is to say LCHF is a free-for-all where we can forcibly/consciously overfeed ourselves and expect to be healthy in the long-term... any more than forcibly UNDER-feeding (aka ELMM) leads to health and happiness :-)

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All comments

  1. Nick
    Look up the All Blacks and their diet, you'll see how it can be beneficial...
  2. Naomi
    3 weeks now on LCHD and have not lost weight. I barely eat that much, and strictly eat low carb with more fat than protein... maybe a glass or two of red wine is my only fault...
    Is this diet not made for me?
    Reply: #212
  3. Naomi
    Another question, using the Ketosticks, the ideal color is 50 (salmon red) or should I have to get to 100, dark red color?
    At the moement ketostick dont pass 50 salmon red color. Am I in ketosis and should I be loosing weight?
    At the moment, no loss.
  4. 1 comment removed
  5. Bruce
    This sure does not apply to me. I’m three weeks into the keto diet and I’ve only lost 4 pounds. I initially lost 8 and then gained 4. Now I’m stuck with no loss evident. What’s happening? All that keto flu for nothing?

    I am not cheating on the carbs so I can only conclude that I am overeating, having too much cream with my coffee, snacking when I am not hungry, portions that are too large, and so on. I can’t believe that You can lose weight on this diet when you’re consuming way more calories than you need. It doesn’t make sense.

  6. 4 comments removed
  7. Laura
    I think something is missing in this article. Metabolic health!

    A metabolically healthy individual may be able to overeat on LCHF but someone who is metabolically unhealthy and weight-loss resistant even on a ketognic diet will NOT be able to overconsume calories without gaining weight.

    The individual in this article was clearly at his ideal body set-point and his metabolism was doing what it should to maintain homeostasis. Please don't think that a person on a weight-loss journey can overeat as many calories as they want (as long as they're low carb) and won't gain weight.

  8. Dan
    Yeah (my opinion) LCHF and keto works because you are passively calorie counting. Cutting down carbs helps with potential excess calorie intake and if you think in normal eating terms then its hard to keep carbs to 20 grams. And the carbs passively controls the calory intake. If you abuse this by consuming very large amounts of close-to pure fat you likely will destroy the weight loss no matter the carbs.
  9. Lise
    What is LCHD?

    3 weeks now on LCHD and have not lost weight.

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