How to Test the ‘Metabolic Advantage’ of Fad Diets Using SCIENCE™


A lot of people read various fad diet books and are drawn in by them. There is no shame in this; The line they usually sell is very tempting. ‘Lose weight without dieting’ or ‘Lose weight without counting calories…Eat as MUCH AS YOU WANT!’ is a really hard thing to resist when trying to lose weight. We all want a shortcut to success, it’s just human nature. Unfortunately, in dieting as well as life, there really are no shortcuts to success. That old adage ‘Successful people are those who do what unsuccessful people are unwilling to do’ is really true. If you want to lose weight, it’s going to take old fashioned hard work. In weight loss, this means you must be calorie negative to lose weight. That is, you must consume less than you expend.
Now, you can disguise that ‘hard work’ as something else (as in the case of low carb diets), but the bottom line is, you still have to be calorie negative or you will not lose weight. However, I know there are those that will disagree with this based on a combination of anecdotal evidence and very badly written books full of logical fallacies (such as those by Atkins or Taubes). That’s why I think everyone should test it for themselves, and in this post, I’m going to show you how to scientifically evaluate fad diet claims on your own so you can draw your own conclusions.
First, realize that this protocol is designed around a low-carb diet, but can be applied to pretty much any fad diet with minor modifications. Second, realize that it takes consistent dedication on your part and a small amount of (relatively) inexpensive equipment. Let me repeat the first part of this, as it’s very important: Testing something correctly requires consistency and absolute dedication to accuracy. You cannot let yourself be affected by the results. If you do, you invalidate the test. It will only take a month, if you follow precisely, and that one month may save you years of BS yo-yo dieting, so it’s well worth it.
Finally, in some cases below I will recommend equipment, simply because it is what I used and I have had good results with it. That being said, I do not receive any kickbacks for any of this stuff. In all cases, I bought it on my own dime, used it, and liked it, so I recommend it if you have no other solution.
Now that that’s out of the way, let’s move on with the how-to.
First, you will need some equipment, some of which you may already have:
  1. A good, accurate, body weight scale.
  2. A small, portable, accurate food scale. I recommend this one for $10 on Amazon.
  3. BodyMedia FIT (or Bodybugg, if you already have that)
Some words about the equipment. For the body scale, make sure it is accurate with itself. It doesn’t really matter too much if it is accurate with your Doctor’s scale, but it must be accurate with itself. One way to test this is to step on the scale multiple times, back to back, placing your feet in slightly different locations each time. With some cheaper scales, you will get different readings depending on where you step. This is really important. I have seen scales be as far as 5 pounds off, which is a huge jump. If your scale is really far off, you need to either figure out a way to make sure you always step in the same spot every day, or buy a new scale (I recommend the latter). If you buy a new scale, when you get it home, perform the same test. If you don’t get good results, take it back and trade it in on a different model. Rinse and repeat until you find a good one.
For the food scale, you really need to make sure it’s portable, because you need to carry it around with you. No, I’m not kidding. So, make sure it fits in your pocket or purse. Either that or make a pact with yourself not to eat out at a real restaurant until you are done with the test.
Finally, on the BodyMedia FIT, you can substitute a GoWear or BodyBugg (they are the same thing, made by the same company, etc), but in my opinion, you really need one of these three. This is the only remotely accurate way to track your caloric expenditure that doesn’t involve a lot of time and guesswork. The standard way of determining your average caloric expenditure is to track what you eat and what you weigh meticulously for a month, then do some math. If you lose weight during that month, you expended more calories than you ate. Say, for example, you lost 5 pounds over the month. This would mean that you most likely expended around 17,500 calories more than you ate, for a daily deficit of around 583 calories. So, if you ate an average of 3000 calories a day, you should be calorically neutral on a diet of 3583 calories a day. Maybe. Possibly. You hope.
Seriously, there is a LOT of guesswork involved in doing it based on intake and weight. There’s a whole portion of the equation that you have zero info on. For example, you have no idea if when you eat the extra 583 calories, if you spontaneously move more to burn more and still end up at a slight deficit. There’s a lot of other factors too, but the bottom line is that the whole thing is a LOT of guesswork that usually takes several months to nail down (and even then, isn’t terribly accurate day to day). By using the BodyMedia FIT, you will know how much you expend each day, within around 10% accuracy, immediately. And you will know daily when/if you go over under, and can immediately adjust. This is perhaps the most important part of this whole test, so if you aren’t going to use one of these devices, please stop here. I do not want to read a later post telling me I am wrong because you were too cheap to perform the test properly. Do it correctly or don’t do it.
Now, on to the protocol. First, let’s talk about your general routine:
  1. Weigh yourself, unclothed, at the same exact time every day (I recommend doing it right after you wake up). It needs to be at the same time and unclothed to remove all possible variables and make it as accurate as possible. Record your weight in your log (I recommend DailyBurn, which is free and decent).
  2. Weigh/measure every single thing that goes into your body and log it (again, using Dailyburn is my suggestion). Everything means everything. Alcohol, fruit juices, a single french fry you steal from your spouse’s plate, chewable vitamins, everything. Do not estimate. Let me repeat that: do not estimate. It is a well known fact that fat people under estimate and skinny people over estimate, and you will never know by how much. Just don’t do it. You bought the scale for a reason; use it. I talk about how to do this accurately in this post.
  3. Once per week, on the same day at the same time, measure yourself. I suggest you measure your whole body (shoulders, chest, biceps, waist, thighs for guys and bust, biceps, waist, hips, thighs for girls), but at the very least you need to measure your ‘fattest’ body part. This is to help determine if the weight you ‘lose’ is fat, muscle, or water. Alternately (and a much better solution, if available), you can get a bodyfat measurement (dunk tank, DEXA scan or bodpod only, as the others are not accurate enough) right before week 1, 3, 5, and 6.
Now that you’ve got an overview of what you have to do in general, let’s talk about the weekly segments, outlined below:
  • Week 1: Calibration
  • Week 2: Induction
  • Week 3 and 4: Induction or Maintenance
  • Week 5: Return to Normal Eating
During week 1, you are just going to be getting your data calibrated. So, you will eat normally and maintain your normal activity level. After a day, you should have a good idea whether or not you are calorically neutral. If not, adjust your diet to be calorically neutral on a day-to-day basis. This means, using the data from your BodyMedia, eat more or less to make sure your expendature is within about 5% of your intake. 
Week 2 is where you begin ‘dieting’. If your diet has an induction phase (ala Atkins), begin it here. For ketogenic diets in particular, kick it off as quickly as possible by eating zero net carbs (or as close as you can). You should be able to enter ketosis in a week if you eat very low carbs (use keto sticks as a guide).
However, it is very important that you maintain neutral caloric balance. This will likely mean that you have to force yourself to eat. This is why low carb diets tend to work, BTW. People get very, very sick of eating the same crap over and over and tend to eat less on their own. You will have to buck this trend, which likely means you will have to force some food down. Do it for the science.
Week 3 will either be your second week of induction (if you aren’t in ketosis yet) or will begin your maintenance phase. If you are still showing tan on your keto sticks, keep on the induction diet. Some people will never see a change in keto sticks, even when in ketosis. You may be one of these people. If so, just stick with the induction diet for weeks 2-4 to make sure you are staying in ketosis (since you have no real guide as to when you are going out of ketosis). Otherwise, enter maintenance. Again, you need to remain calorically neutral, so force down however much meat you need in order to do that.
One note here: Splenda (and some other sugar substitues) actually contain calories in the form of sugar. It’s a trick that they are able to list them as zero calories (see here for details). Splenda, for example, actually has about 30% of the calories of sugar, all of them coming from carbohydrates, so if you eat or drink a lot of it, you will never enter ketosis.
Week 5, you will return to a normal diet (staying calorically neutral). At the end of week 5, you are going to analyze results. You should see something like this:
  • Week 1: No weight gained
  • Week 2: OMG, I LOST 5 POUNDS!!!!
  • Week 3: No weight lost
  • Week 4: No weight lost
  • Week 5: I gained the 5 pounds back…:(
So, let’s talk about the expected result, and then I’ll talk about some possible anomalies.
First, in looking at the expected result, I am obviously expecting you to lose about 5 pounds when you start your ketogenic diet and gain it right back when you come off of it. That is correct. However, it’s not fat that you lost/gained, its water.
It’s a well known feature of ketogenic diets that they dehydrate you slightly. This is why almost everyone tends to drop a lot of weight shortly after starting one, and gain most or all of it back when they come off of it. This is where the measurements come in, as well. Take a look at your beginning measurement of your ‘fattest’ body part, and compare it to the measurement you took right after you lost the weight, the measurement right before you gained it back, and the measurement right after you gained it back. Chances are, they are identical (or very, very close). This is a pretty good indication that you didn’t actually lose any fat. Of course, if you went for the body fat tests, you will know for sure that you didn’t lose any fat. 🙂
Anyhow, the expected result is that you won’t lose any actual fat on your fad diet. Even if you lose weight, that really doesn’t matter. What we all actually want to lose fat, it just so happens that measuring how much fat you are losing is really hard to do consistently. But this is a pretty decent way of approximating it.
So, what about some expected anomalies? Well, one of them would be that you actually gain or lose a little bit of real weight/fat. Why do I expect this? Because, as I mentioned earlier, the BodyMedia FIT is only about 90% accurate. So, if it says that you are calorically neutral at 3000 calories, you may actually need as much as 3300 or as little as 2700. That 300 calories a day, compounded over 30 days, could result in up to 3 pounds of actual fat lost or gained. So, if you only gained/lost 3 pounds of fat or less, I still consider that proof that the fad diet doesn’t work. You were within the margin of error for the test.
Another expected anomaly can occur in women. Women tend to retain water due to their menstrual cycles, and that makes this type of month-long test very difficult to do if not timed just right. My suggestion for women is to take this under advisement and use the measurements as more of a guide than body weight.
What if you don’t fit either of those categories, and you lost (or gained) real weight? First and foremost, double-check your data. Add up the caloric intake of each day and then subtract the caloric expenditure of each day. Since you’ve been logging it all, this should only take a few minutes, and you will likely see your ‘anomaly’ right there in the data.
If not, my suggestion then is to extend the test for three more weeks, but this time, eat a balanced (non-fad) diet that has the same calorie totals as you were eating on the fad diet. Track all of the same things, in all of the same ways, and see if you get the same results. If the result is the same, that should be all the proof you ever need that calories matter. If not, then maybe you need to post your own blog up with your results for the world to scrutinize, as you are the only creature in existence for whom the first law of thermodynamics does not apply.
Happy experimenting 🙂

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    • #2 by Brian Hill on February 12, 2012 - 2:47 am

      Please read the responses by Lyle McDonald to he article in that very same link. Here’s an excerpt:
      As well, direct research (by Brehm) shows that there is no difference in resting metabolic rate for ketogenic vs. carb-based diets; the thermic effect of food was higher in the high-carb condition. If there were a true metabolic advantage in terms of energy expenditure for ketogenic diets, someone would have been able to measure it by now. They haven’t and they aren’t going to and all of the theorizing about it doesn’t change the fact that direct research hasn’t supported the concept.

      Now, protein has the biggest impact in terms of the thermic effect of food, switching out carbs or fat with protein tends to increase the energy out side of the equation but you have to make pretty large scale changes for it to be particularly significant. I’d note that protein also tends to be the most filling of all the nutrients and studies show that increasing dietary protein intake tends to cause people to eat less calories. Which is another huge confound; if increasing protein makes folks spontaneously eat less, it looks like it was adding the protein per se that did the magic. But it wasn’t, it was the effect of increasing protein on total energy intake that caused the fat loss. Like I said, a subtle confound that people tend to miss a lot.

      Here’s Lyle’s article on this subject:
      http://www.bodyrecomposition.com/fat-loss/the-energy-balance-equation.html

  1. #3 by Anonymous on February 19, 2012 - 9:11 pm

    hey, this is studtotal from fitocracy. interesting analysis. some semi-random thoughts: (1) there are no essential carbohydrates. the only macronutrients essential to humans are proteins and fats. people have “cured” themselves of type 2 diabetes by adopting low carb diets. (2) anyone with the discipline to see this experiment through to completion has more than enough discipline to (a) not be fat in the first place and (b) to lose weight on any diet that merely restricts calories.

    overeating carbohydrates (chips, pretzels, candy, sugary drinks) is the cause of most weight problems. whether it is possible to lose weight–perhaps even a greater amount of weight–on a different diet isn’t the point. regardless of whether there is an objective “metabolic advantage” to low-carbing, the reality is that an average overweight american can stick to a low carb diet and get quick results without counting calories, measuring, or otherwise applying any kind of focused discipline, with the added advantage of never having to come off the “diet,” because there are no essential carbs.

    Low carb isn’t the answer to everything, because athletes need carbs for optimal performance. Low carb isn’t for elite athletes, except perhaps bodybuilders, and then only around contest prep time. But your average lazy american who stops having pizza, soda, and french fries can see a real and lasting difference.

    did you see the movie fathead? http://www.fathead-movie.com/ It’s available on hulu and netflix streaming.

    • #4 by Brian Hill on February 19, 2012 - 9:42 pm

      Thanks studtotal. You’ve brought up some interesting points, I’ll try to speak to them individually.
      1) I am not in disagreement here. Having been on a completely carb-free diet before, I am more than aware that carbs are not necessary, though lack of carbs can limit muscular performance in some instances.
      2) That’s a good point, and well taken, but I think there is a fundamental difference in intended audience. I wrote this more for the fitness enthusiast who believes in all of the low carb hype and ‘calories don’t matter’ dogma. My point is that this is a testable theory, so before you send someone down a bad path, test it for yourself.

      I don’t disagree that you can lose weight on a low carb diet, I did it once upon a time myself. Furthermore, if I ever need to cut a lot of fat really quickly, I will likely do so using a PSMF, which is a low carb diet. I just wanted to make clear that the reasons lo carb diets work are still due to energy balance, not pseudo-scientific voodoo.

      Regarding Fathead, I haven’t seen it, mostly because based on what I’ve heard about it, it’s highly biased towards the ‘calories don’t matter’ camp, and I’m just about as far outside of that camp as you can get.

  2. #5 by Anonymous on February 20, 2012 - 2:31 am

    studtotal again. tried to post before, but got called away from the keyboard and my post went poof. sounds like we agree on the basic facts on the ground. i think all nutrition advice needs the caveat “but there’s more to it…” as in, “you only lose weight if you eat fewer calories than you expend, BUT THERE’S MORE TO IT: you will probably find it easiest [if you’re a typical lazy american] if you just restrict carbs.” OR: “low-carbing is a great way to cut weight, BUT THERE’S MORE TO IT: you’re never gonna recover from 3xweek balls-out lifting on just trace carbs.”

    good stuff.

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