“You Just Gain It All Back”

This article is the second in an occasional series about the dumb things people say about the low-carb lifestyle.

At some point in the history of the English-speaking world, the way people understand the word “diet” changed.  (No linguist I, I cannot tell you exactly when this happened.)  If you say to the average native speaker of English, “I am on a diet,” your listener will understand you to say that you are on a temporarily restricted food regimen for the purpose of losing weight.  And because we hypothesize that cutting calories leads to weight loss, your listener will further assume that you are eating less food and fewer calories than people who are not on a diet.

Well, I have news for you, friends – we are all on a diet.  You are on a diet.  I am on a diet. The obese woman browsing the aisles in the plus size department is on a diet.   The skinny 20-something hacker in the next cube is on a diet.  Your dog, cat, guinea pig, hamster, Japanese fighting fish, Vietnamese pot-bellied pig, and/or turtle is on a diet.  Cheetahs, great apes, rhesus monkeys, emus, rattlesnakes, scorpions, and dolphins are on a diet.  The only animals that are not on a diet are dead animals (and hunger strikers).

This is because, well, you gotta eat something.

The Merriam-Webster definition of diet is as follows:

Main Entry:

¹di·et 

Pronunciation:

\ˈdī-ət\

Function:

noun

Etymology:

Middle English diete, from Anglo-French, from Latin diaeta, from Greek diaita, literally, manner of living, from diaitasthai to lead one’s life

Date:

13th century

1 a: food and drink regularly provided or consumed b: habitual nourishment c: the kind and amount of food prescribed for a person or animal for a special reason d: a regimen of eating and drinking sparingly so as to reduce one’s weight <going on a diet>2: something provided or experienced repeatedly <a diet of Broadway shows and nightclubs — Frederick Wyatt>

Note that the first two definitions of the word refer to what we normally eat, and it is only the third and fourth definitions that refer modifying normal food intake for specific purposes, and it is only the fourth definition that introduces the subject of weight loss.

I wax pedantic here because it is essential to my argument that the definition of a low-carbohydrate diet be clearly understood.  Low-carb is a diet in the first and second senses of the word.  When you adopt a low-carb diet, you are changing the food that you regularly, habitually consume.  Depending on your reasons for following the diet, it might be a diet in the third sense, too:  you might be following a low-carb diet for the special reason of managing your blood sugar or triglycerides.  But it is not a diet in the fourth sense.  The fourth sense implies that once weight is lost, you abandon the diet in favor of your old ways.  (This is implied by the fact that the definition refers to reducing weight, not maintaining weight.)

It’s so easy to find studies that show that people on low-carbohydrate diets gain weight back at equal or greater rates than people on low-fat diets that I am not even going to bother looking them up.  (This, as textbook authors sometimes say, is left as an exercise for the reader.)  But those studies make a fundamental assumption that diet means definition 1d, above – a regimen to reduce one’s weight.  And this assumption carries with it that second assumption, which is, once the weight is lost, we go back to eating the way we always did.

I am in no position to argue that you can go on a low-carb diet for several weeks or months, lose all your excess weight, and then return to a high-carb diet and maintain your newly reduced weight.  I don’t even want to argue that position, because I know it’s not true.

What I do want to suggest is that, if you continue carbohydrate restriction indefinitely, you will manage your weight indefinitely.  As far as I know, no controlled studies have been done comparing low-carb dieters with low-fat dieters for periods of 1, 2, or 5 or more years.  These studies are urgently needed before anyone can confidently argue that, while sticking to a reduced-carbohydrate regimen, a dieter can lose a bunch of weight and then gradually gain it back, while still sticking to the low-carb diet.

In the meantime, it’s not difficult to find anecdotal evidence that the low-carb helps maintain weight.  Here are just a few examples, each of which showcases multiple success stories:

http://www.lowcarb.ca/stories.html

http://www.e-clipse.com/success.htm

http://www.bellaonline.com/subjects/5850.asp

Let us be clear about the role of anecdotal evidence in scientific research, lest critics of the low-carb diet use this to trip me up.  I am well aware that anecdotes don’t, in themselves, prove anything.  Results that do not come from a well-designed study may not adequately control for the variable being tested.  Confounding variables might be included (maybe people who eat low-carb diets also tend to do something else that is actually responsible for the effect observed).  Careful measurements may not have been taken.  The person providing the anecdote may be mistaken, or deliberately lying, or may misunderstand the results of the lifestyle change.  There are many reasons that anecdotes are not sufficient to prove or disprove a hypothesis.

But the thing that anecdotes are very, very good for is generating hypotheses.

If enough people claim that low-carb diets helped them lose weight and keep it off, if Dr. Robert Atkins, Drs. Mary and Mike Eades, Dr. Barry Groves, and many other medical professionals claim that they have successfully treated hundreds or even thousands of patients for obesity with low-carbohydrate diets, if you can Google the phrase “low carb success stories” and find heaps of people who claim to have succeeded on low-carb – doesn’t that suggest something?  Might we hypothesize that low-carb diets are effective long-term weight loss strategies?

Any good science textbook will tell you that hypotheses, by definition, must be both testable and falsifiable.  Testable means it must be possible to conceive of tests that can provide evidence to support the hypothesis.  Falsifiable means you can also conceive of tests that can prove the hypothesis wrong.  The responsible thing for the scientific community to do, when confronted with a mounting body of anecdotal evidence that suggests a hypothesis, is to go about the work of testing this hypothesis.

As far as I know, this kind of research has never been done on the long-term efficacy of carbohydrate-reduced diets.  (If I’m wrong, I hope a reader will call this research to my attention.)  So all we have, then, is a large body of anecotal evidence.

We know that you gain weight back when you go off the diet.  But there is little scientifically tested evidence that tells us whether you gain weight back if you stay on the diet.  And since virtually all proponents of low-carb diets indicate that carbs must be restricted to maintain weight loss, it is that proposition that must be tested.  Until it is, we simply can’t say one way or another whether low-carb diets succeed in the long haul.  Showing that subjects gain weight if they abandon the diet is worthless, since the diet is not meant to be abandoned.