Is a Zero-Carb Diet a Good Low-Carb Option?

Chuck Roast on a Bed of Lettuce
Some people do very well on a Zero-Carb Diet
While others do not!

Do the laws of physics still apply if you keep your carbs very low?

Many people believe they don't.

For years, low-carb dieters have been trying to disprove the energy equation, without success. Here's what happened when two people tried to go zero carb.

The first time I was introduced to the idea of going zero carb was when I read a thread at Jimmy Moore's old forum called, "Jeff's Fat Experiment."

I didn't know who Jeff was, other than he was someone from the Magic Bus site (a carnivore forum). He decided to try a zero-carb experiment at the end of 2007.

The point of his experiment was to show in a visible way that calories in do not equal calories out -- if you keep your carbs super low. He wanted to prove that the law of physics does not apply to anyone following a very low-carb diet.

The attempt wasn't new.

Low carbers have been trying to discredit the energy equation for a very long time, but so far, they have only succeeded in discrediting physics in their own mind.

A zero-carb diet can be a good low-carb option for those who can't process carbohydrates effectively, but can you actually eat all the calories you want if you don't eat any carbs?

That's what Jeff wanted to find out. He decided to drastically up his calories and fat percentage for 30 days.

The essence of what he did was overeat on a very low-carb diet, sometimes referred to as overfeeding, since he went way over what the calorie theory said his maintenance calories should be.

This experiment took place several years ago.

Two Men Barbecuing Steaks and Chicken
If you don't eat any carbs at all,
can you actually eat all you want and still lose weight?

I honestly do not remember the exact proportions of protein to fat he ate that month. That detail would be vital to know. I just remember that he cut his carbs to the bone, what Dr. Atkins called biologically zero, and reported his daily weight for the Magic Bus folks.

Here's what happened:

Jeff's 30-Day Fat Experiment

Jeff's misconceptions about the energy equation and how the body handles excess energy are pretty common, especially among the low-carb community.

Basically, Jeff believed in the Insulin Hypothesis, which was alive and well long before Gary Taubes presented it to the world. Both Dr. Atkins and Dr. Eades have discussed their beliefs about insulin quite frequently.

Part of the Insulin Hypothesis says that elevated insulin levels are necessary for the body to store fat, so if you keep insulin low, and avoid phase two insulin spikes, you can't store fat no matter how much you eat.

This false notion was disproved scientifically quite a while ago.

Fatty Pork Steaks, Uncooked
There is an alternative fat metabolism pathway that works independent of insulin. When you eat a high-fat diet, such as Jeff did, your body will make additional chylomicrons to transfer all of that fat to the liver. It will also crank up its production of ASP to process it.

This is true for everyone.

However, once in the liver, the liver decides whether to convert those extra chylomicrons to VLDL and burn them for energy, or store them in your fat cells.

ASP secreted by the fat cells plays the same role as insulin when insulin isn't available, either due to a lack of glucose in the diet or insulin resistance. ASP allows the triglyceride encased inside chylomicrons to be removed from the chylomicrons.

Fat removed from chylomicrons does not need insulin to be stored, so what happens to the extra fat you eat has a lot to do with genetics and calorie partitioning. 

One of the most important factors connected to Jeff's experiment is that he wasn't overweight when he overfed.

He was 5 feet 8 inches tall and only weighed 169 pounds. His body fat percentage was 10.9 percent. He was also in his 40s, so we aren't talking about what happens when you try to combine weight loss with low insulin.

We're talking about what happens when someone of normal weight tries to overfeed.

Man running
Jeff's experiment shows what might happen
if you are young, active, and normal weight.

Jeff was most likely on maintenance from what I could deduct from his journal back then, but I honestly don't know his past dieting history -- if any.

Not everyone who turns to a meat-only diet is fat.

Many, like Charles Washington, the author of the Zero-Carb Diet, decide to move to zero carb for althletic performance, rather than weight loss.

During this 30-day experiment, Jeff consumed:
  • 3000 to 6000 calories a day
  • 5 to 15 carbs
  • Over 80 percent of his calories in dietary fat
depending on how you decide to weigh in his coffee and heavy cream.

He did not gain any significant weight during the entire 30-day experiment.

The only day he did gain weight, it was just a single pound.

Jeff didn't weigh himself everyday, so it is possible that this slight bounce upward happened more than once. In the case he talked about, it was after a large, salty meal that included three glasses of alcohol. Alcohol is not allowed on a zero-carb diet.

3 Glasses of Wine: Blue, Red, and Green drinks
The only time Jeff gained weight was after
drinking 3 glasses of alcohol.

By the time Jeff weighed himself again, the pound had come back off.

But does this negate the energy equation?

According to the calorie rule, you'll gain a pound of body fat for each extra 3,500 calories you eat, so Jeff should have gained several pounds of fat. Yet, he didn't.

After eating a massive amount of fat and plenty of protein, Jeff didn't gain any weight at all that month.

His conclusion:

Calories in don't have to equate with calories out.

How are Triglycerides Formed?

Triglycerides consist of three fatty acid chains bound to a single glycerol molecule. This glycerol molecule comes from glycerol phosphate, which is a by-product of glucose metabolism.

Essentially, Jeff believed that if you do everything in your power to avoid blood sugar spikes, such as drastically lower your carbohydrates down to biological zero, there will be very little glycerol around for the fatty acids to bind to.

With a zero-carb diet, or at least a very minimal carb diet, it should be impossible or extremely difficult for the body to store fat because there would be no mechanism to do that.

Hence, the experiment.

However, this is a gross misunderstanding of the way gluconeogenesis works. Since the brain needs glucose to supply one-quarter of its energy requirements, there are several ways for the body to manufacture that glucose.

One way is to use some of the amino acids in all of that protein Jeff was eating, but the body can also make glucose from glutamine, a non-essential amino acid that the body can make from other things.

The Flaws in Jeff's Conclusion

The metabolic pathway for protein is less efficient than it is for dietary fats or even carbohydrate. This means that a large proportion of the calories in the protein you eat is either used or wasted during the process of break down and digestion.

The different efficiency between the macronutrients and how the body metabolizes them affects the rate at which calories are used. Current science estimates that you use 25 percent of a protein food's caloric content just to digest it.

Jeff was trying to disprove the law of thermodynamics, but what he didn't understand was that the laws of thermodynamics are about energy storage. They are not about increases in body mass.

Increased body mass, like body fat or muscle, are the result of these laws and not the law itself.

Every tissue in the body has a different energy value. If less energy comes in to take care of the body's needs, it draws upon the energy it already has stored to make up the difference. If too much energy comes in, the body either has to:
  • store the energy for later
  • ramp up your resting metabolic rate
  • make adaptions that use the energy
If energy isn't stored, it has to be used in some way, which is exactly what the law of thermodynamics says. Whether you store that excess energy or use it in a different, non-typical way, the law requires the body to find some way to balance what's going on.

Every time you make a change in the equation, as Jeff did by overfeeding, it forces the body to make other changes to bring everything back into balance.

The energy equation is not static.

It has to bend to fit what's happening, and storing excess energy as fat is only one way to fulfill the law.

Balancing Scale: 3-D Figure is Climbing into One Side

There are dozens of ways the body can change energy expenditure to bring the body back into balance without storing it as fat.

For example, some people's resting metabolic rate goes up during periods of overfeeding. They burn more calories while watching television than they normally would.

Other people might suddenly:
  • become more active
  • begin to unconsciously fidget a bit more
  • get up from their desk more often
  • find themselves absentmindedly pacing the room
  • or suddenly get more done throughout the day than they normally would
While this might sound incidental, the extra calorie burn can be as high as 1,000 calories a day or even more.

Expectations are not Reality

Shrimp Salad Can Help You Eat at a Calorie Deficit
Eating at a calorie deficit doesn't mean you will
lose weight every single week

Just because someone decided that a 500 calorie-per-day increase should pack on an extra pound of fat by the end of the week, that doesn't mean it happens that way in the real world.

This part of Jeff's experiment was true. The energy equation isn't mechanical. It's fluid. However, that adaptability doesn't mean the laws of physics are invalid. The:
  • elevated cortisol
  • water fluctuations
  • ability to easily burn fats for fuel
  • energy needed to process extra food intake
  • increased spontaneous movement
  • increased sleeping and resting metabolic rate
can change your maintenance calorie requirement by thousands of calories, depending on your genetics, insulin sensitivity, age, and other factors.

Linda's Very Low-Carb Experiment at Maintenance

If Jeff's conclusion was true, then someone who was already at maintenance, living at a very low-calorie level to maintain that weight, should be able to drop their carbs from the typical 35 grams a day to 5 grams or less, and thereby, be able to raise their calories without gaining weight.

So, Linda from the Linda's Low Carb Recipes web site decided to give Jeff's idea a try.

Linda weighs less than the standard weight charts say she should, but she has to keep her calories less than 1,100 a day or she begins to gain weight. Instead of eating between 5 and 15 carbs as Jeff did, she created a very low-carb diet instead.

Very low-carb diets often include eggs and a bit of cheese or heavy cream to make them easier to sustain, but rarely include more than 5 grams of carbohydrate per day.

For the first week, everything went well.

But then, suddenly, after about seven days, Linda's weight started bouncing. In a carb depleted state, the body never recovered, or adapted, even though she wasn't eating very many carbs.

Eventually, she moved back to the low-carb diet her body had adjusted to, lowered her calories, and was able to return to her normal maintenance weight, provided she kept her calories low.

Unlike Jeff, she cannot maintain without following a low-calorie diet.

The different response that Linda got to dropping her low insulin levels even further merely emphasizes the point that weight management isn't about the carbs or even the insulin.

In my own experience, the degree of stress that carb restriction places on the body has a lot to do with whether you'll be successful, or not, but so does your body's ability to burn fat for energy or your body's ability to use any excess energy you take in, rather than store it.

The Bottom Line

No matter what Jeff said, his 30-day fat experiment did not prove that calories don't count. It just proved that some people can overfeed without gaining weight due to the way the law of thermodynamics works.

Others, like Linda, will have to stick to a low-calorie diet for life if they want to maintain goal weight. Just going low in carbs might not be enough.

When it comes to weight loss, the energy equation is far more complex than what I've presented here.

Since this blog post was about what happens when carbs are super low and calories are higher than maintenance, there are a lot more factors that comes into play when trying to carve off the pounds.

It's not just a matter of carbohydrate restriction. Reducing your carbs is only one aspect of making low carb a way of life.


  1. It may be hard to start this kind of nutrition, but at the end, most of the people eventually see the benefits of this diet. I know many people who successfully applied this diet in conditions like epilepsy, but some also find it effective in weight loss.

  2. Good post. I'm a stubborn loser and so was thinking about a fat fast which is effectively a zero carb diet but calorie-restricted as well. BTW, I think that the term "zero carb" is a misnomer when you consider that even eggs and black coffee have a small number of carbs. I was unaware of the alternative fat metabolism pathway which probably explains my continued failure at significant weight loss even when eating at a ketogenic level of carbs! What are your thoughts about fat fasts in view of the alternate pathway, since you are eating high fat but significantly restricting calories? (BTW maybe I need to read your post a few more times - there's so much info in there as usual lol!) If I still can't lose, I'm going back to the Thin So Fast plan, although it was tough.

    Thanks for another lesson Vickie - just when I think I know it all hehe :)

    1. Thanks. The Fat Fast works remarkably well for those who are extremely insulin resistant and can burn fat for energy because it cuts protein and calories to the bone. You can't stay on it indefinitely, since it's too low in protein, but what some people have done (those who couldn't lose any other way) is do a fat fast for 7 days, then 3 weeks of Induction, then go back to the fat fast.

      I have never tried to do one.

      Some people really do zero carbs, but yeah, eggs and coffee have a bit of carb in there.

  3. I was maintaining my significant weight loss for over 7 years but had to stay <20g carbs and about 1,100 cal to maintain. A horrible Rx caused me to gain about 7 lbs that I could not drop. I read Amber O'Hearn about going to zero (just meat, fish, and fats), and I tried it for 30 days.

    I was amazed because I craved fat and stopped counting calories (because I knew I was way over my 'limit'), but those excess pounds just melted off! I now can easily maintain if I stick to this WOE, and I actually like it
    because I've always been a meat eater. I suspect that I have a strong negative reaction to carbs because with even 10-20g, I have to seriously restrict calories to avoid gain.

    It just shows how each of us has to find the best WOE for him/her self. We're all different.

    1. Thank you so much for sharing your experience! I'm so glad to hear that zero carb worked well for you. Metabolism can crank up for all sorts of reasons. Looks like you found the perfect diet for you! Congratulations! I love hearing about success stories.


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