Two Dieting Myths Debunked

These days, many diets seem to have an almost cult-like following.

They'll often single out hormones (such as insulin) or individual nutrients (like carbohydrate) as the "Holy Grail" when it comes to losing fat, with each diet based on a set of strict "rules" that must be followed at all times without question.

In truth, many of these rules are nothing more than myths — two of which have been effectively debunked in a study that I stumbled upon this week.

I'll explain what they are in a moment.

First, I want to take a closer look at what actually happened in the study.

Australian researchers took a group of 33 overweight or obese subjects and put them on one of 3 weight loss diets — low carbohydrate, low fat and high unsaturated fat — for 8 weeks and on the same diets in energy balance for 4 weeks [1].

Here's what the nutrient composition of each diet looked like.

Low Fat
Carbohydrate = 70%
Fat = 10%
Protein = 20%

High Unsaturated Fat
Carbohydrate = 50%
Fat = 30%
Protein = 20%

Low Carbohydrate
Carbohydrate = 4%
Fat = 61%
Protein = 35%

The only thing the diets had in common was the fact they provided the SAME NUMBER of calories.

And the result?

All three groups lost weight. But those on the low carbohydrate diet lost slightly more weight — 8 kilograms (17.6 pounds), compared with 6.7 kilograms (14.7 pounds) in the low fat group and 6.4 kilograms (14.1 pounds) in the high unsaturated fat group.

The figure below shows the average weight loss in each group over the 12 week study.

At first glance, this might appear to be just another study showing superior weight loss with a low carbohydrate diet.

What are the two myths that have been debunked here?

Myth #1. There's a "special" combination of nutrients that will let you lose fat irrespective of calorie intake.

As well as tracking weight loss, the researchers also used dual-energy, x-ray absorptiometry (DEXA) to assess changes in body composition. DEXA is an extremely accurate way to measure changes in fat loss, and is far more reliable than the skinfold calipers or body fat scales often used in health clubs.

Although the low carb group lost the most weight, this was mainly due to the fact that they lost more lean mass than subjects on the other two diets.

In terms of fat loss, which is what most people are interested in, the results show "no significant difference" between groups.

In other words, despite some very big differences in nutrient composition between the three diets, fat loss was much the same in all three groups. That's because calorie intake was also much the same.

Contrary to the claims of many, calories DO count.

Myth #2. The key to weight loss is to control insulin.

You'll read a lot about insulin "turning off" the fat-burning switch, and that no matter what else you do you won't make any progress if your insulin levels are "out of whack."

If this were true, you'd expect to see similar changes in insulin levels given the fact that all three groups lost a similar amount of fat.

But this wasn't the case.

The low carbohydrate diet lowered fasting insulin levels by 33%. This compares to a 19% fall on the high unsaturated fat diet and no change on the low fat diet.

Yet despite these differences in insulin levels, fat loss was virtually identical on all three diets.

So much for insulin being "the key" to weight loss.

Yes, insulin does have a role to play in fat metabolism. But so do other hormones. It's a mistake to focus on one and ignore the rest.

While there are a few important principles to keep in mind when it comes to nutrition and weight loss, the secret to success is still to consume fewer calories than you burn. Don't be seduced into following an overly complicated diet masquerading under the guise of a "new and revolutionary" approach to weight loss.

In fact, once the basics are in place, you can lose weight on ANY diet just as long as you stick to it.

There's no need to complicate things by worrying about insulin, the glycemic index, meal frequency, not eating carbs after 7pm or any of the other things that don't matter even half as much as some people say they do.

As with most things in life, the simple approach is usually the most elegant one.

About the Author

Christian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Muscle & Fitness, Fit Pro, Zest and other popular fitness magazines.

If you want better, faster results from the time you spend in the gym, click here now for instant access to his step-by-step muscle-building and fat-burning workout routines.

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Reference
1. Noakes M, Foster PR, Keogh JB, James AP, Mamo JC, Clifton PM. (2006). Comparison of isocaloric very low carbohydrate/high saturated fat and high carbohydrate/low saturated fat diets on body composition and cardiovascular risk. Nutrition & Metabolism, 11, 3:7