There's no one who hasn't heard it before.
"I'm going to eat low carb foods for a while, I'm trying to lose weight."
But just how effective is low carbohydrate dieting for weight loss and performance? Is it really what it's cracked up to be?
REDUCED POWER - LESS GROWTH
One of the big problems with low carbohydate dieting is that your energy output decreases (1).
Not good news when you're trying to increase your power in the gym to either gain muscle or lose bodyfat.
As I like to say often, you need petrol in your tank to get to your destination!
Furthermore, other research (2) has found that when low levels of muscle glycogen (stored carbohydrate) are detected, post-workout signalling related to muscle growth is hindered.
Also, another study (3) compared both and high and low carbohydrate diet, and found the low carb group lost more strength, suffered a slower recovery, and the worst part - had lower levels of protein synthesis.
BLAME IT ON THE CELEBRITIES?
The other issue is the tabloids and celebrities, who spruik the low carb diets to people right around the world.
I have distinct memories of reading all sorts of garbage relating to celebrities and weight loss tips when I was young.
I remember one "no food after 7pm" and "extra low carbs" - in reference to one popular actresses "secret diet tips".
From the news stand, it's accepted as gospel - and one needs to read articles like this to realise they've been brainwashed!
THE TWINKIE PROFESSOR
Who could ever forget the famous Twinkie Professor, who lost a massive 12.2 kgs by eating.......Twinkies? (4).
Yep.
He blew this low carbohydrate myth for fat loss right out of the water.
The common misconception is that an insulin spike resulting from carbohydrates leads to body fat.
Well if that were the case, then ANYTHING containing carbohydrates would trigger body fat storage.
But this just ISN'T reality, just ask the Twinky professor. It's largely about over all calories.
Now obviously I don't condone a diet like this at all, but to illustrate the point, it's important to mention it.
EVEN WHEY PROTEIN PROVIDES AN INSULIN SPIKE!
Believe that!
It blows most people away when they discover that this is the case. In fact, the spike from a whey protein shake is even larger than white bread! (5).
One should focus more on a calorie deficit whilst getting sufficient protein and fibre, and making up remaining calories with carbs and fats - whilst forgetting about the whole low carb notion for fat loss all together.
Low carb diet foods are not going to miraculously change your waisteline.
CARBS FOR APPEARANCE
A lot of people want their muscles to look big and full.
Glycogen (stored carbohydrates) is a hydrated molecule, attracting about 3-4 grams of water per gram (6).
So eat more carbs, and get more water in your muscles, making them FULLER and BIGGER!
Why would anyone argue with that?!
Not to mention that the more fluid inside your muscle means your creatine supplementation can be even more beneficial, as creatine will also help pull more water into your muscles.
Hmmm. Not looking good for the "low carb dieting" approach is it?
And we beat on.
MORE POORLY DESIGNED STUDIES
So where else did the rubbish spawn from?
Well, the low carb studies have all been poorly designed.
What we’re actually looking at in these studies is a high-protein, low-carbohydrate diet vs. low-protein, high-fat diet, and the former wins every time.
But we can’t ignore the high-protein part and say it’s more effective because of the low-carb element. That's not a true comparison.
For instance, studies have examined a LOW CARB and HIGH PROTEIN diet, and compared it to a LOW PROTEIN and HIGH FAT diet - without keeping the protein intake high.
But it's the HIGH PROTEIN that is important to fat loss - NOT the LOW CARB approach!
THE BETTER RESEARCH
So what happens when a low carb and high carb approach is taken - when the right amount of protein is included in both studies?
Well, there's no significant difference in fat loss at all (7).
Furthermore, another study showed that when you reach your required protein intake for dieting, which is 2.3-3.1g/kg/day (8), how you split your remaining calories over fat and carbohydrates, makes no real difference (9).
Your protein intake is so important to fat loss - but that's another whole article in itself for another day.
So nail your PROTEIN - that's what matters, NOT how low your carbs are.
ALSO - CARBS CAN MAKE YOU FEEL FULLER!
How hard is it fighting hunger when you're aiming for fat loss?
Research (10,11) shows that carbs are superior to fat when satiety is brought into the picture. You have to stay full to prevent any over eating.
Now I must point out that this is for breakfast, and this COULD possibly be different at various times of the day, however, the science cannot be ignored.
Another extensive review (12) into low carb/high fat dieting finds no performance benefit either.
You can be sure that in the athlete and coaching world - there's not one diet that doesn't slip under the radar.
And no elite athletes are getting into low carb/high fat diets for the edge! To quote from the review:
“When performance was measured at high intensity after a longer period of adaptation, it was at best maintained, but in most cases attenuated, compared with consuming a carbohydrate-rich diet.
The review also points out:
“When adaptation to a fat-rich diet was performed over longer periods, studies where performance was tested at moderate intensity, 60 to 80% of maximal oxygen uptake, demonstrate either no difference or an attenuated performance after consumption of a fat-rich compared with a carbohydrate-rich diet.
OK - THEN WHY DO BODYBUILDER DROP CARBS BEFORE A SHOW FOR FAT LOSS THEN?
I mentioned above that carbs draw water into your muscles.
So when you stop eating carbs for a week to 2 weeks - you will cut the water from your body, giving you a leaner look (13).
Obviously this is the look bodybuilders go for, because they want to look as lean as possible as this is one of the areas they're marked on.
But as they will tell you also - this cannot be maintained. It is merely practiced for a 10 minute posing routine on a stage - not for a lifetime look.
For more on dropping carbs altogether, check out my article here on the Paleo diet.
CONCLUSION
For the athlete, or one looking for strength gains, muscle gains, and optimal fat loss - a low carbohydate diet is NOT the best option.
The right amount of protein and fibre should be the first concern, with carbohydrates and fats to be distributed afterwards.
So pay no real attention to the garbage marketing along the lines of low carb meals and low carb diet recipes - they are NOT a game changer.
A low carbohydrate diet is suitable for the sendentary individual, or one with insulin issues.
But that is another issue entirely.
Those looking for optimal body composition and performance should not be shunning carbohydrates!
"STAY FIT, STAY FLEXED!"
REFERENCES
(1) Miller SL, Wolfe RR. Physical exercise as a modulator of adaptation to low and high carbohydrate and low and high fat intakes. Eur J Clin Nutr. 1999 Apr;53 Suppl 1:S112-9.
(2) Creer A, Gallagher P, Slivka D, Jemiolo B, Fink W, Trappe S. Influence of muscle glycogen availability on ERK1/2 and Akt signaling after resistance exercise in human skeletal muscle. J Appl Physiol (1985). 2005 Sep;99(3):950-6. Epub 2005 May 5.
(3) Benjamin L et al. Dietary Carbohydrate and Protein Manipulation and Exercise Recovery in Novice Weight-Lifters. Energy Metabolism Laboratory, Department of Kinesiology/Exercise Science Program, University of Rhode Island, Kingston, Rhode Island, USA. 2009.
(4) Park M. "Twinkie diet helps nutrition professor lose 27 pounds." CNN News. 2010 Nov 8.
(5) Nilsson M, Stenberg M, Frid AH, Holst JJ, Bjorck IM. Glycemia and insulinemia in healthy subjects after lactose-equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins. Am J Clin Nutr. 2004 Nov;80(5):1246-53.
(6) Olsson, KE et al. (1970). Acta Physiol Scand 80: 11–18.
(7) Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, Sears B. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. Am J clin Nutr. 2006 May;83(5):1055-61.
(8) Helms Er. A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes. IJSNEM. Septermber 20, 2013.
(9) Noakes M et al. Comparison of isocaloric very low carbohydrate/high saturated fat and high carbohydrate/low saturated fat diets on body composition and cardiovascular risk. Nutr Metab (Lond). 2006; 3: 7.
(10) Holt SH, Delargy HJ, Lawton CL, Blundell JE. The effects of high-carbohydrate vs high-fat breakfasts on feelings of fullness and alertness, and subsequent food intake. Int J Food Sci Nutr. 1999 Jan;50(1):13-28.
(11) Cotton JR, Burley VJ, Weststrate JA, Blundell JE. Dietary fat and appetite: similarities and differences in the satiating effect of meals supplemented with either fat or carbohydrate. J Hum Nutr Diet. 2007 Jun;20(3):186-99.
(12) Helge JW. Adaptation to a fat-rich diet: effects on endurance performance in humans. Sports Med. 2000 Nov;30(5):347-57.
(13) Olsson KE, Saltin B. Variation in total body water with muscle glycogen changes in man. Acta Physiologica Scandinavica. Volume 80, Issue 1, Pages 11-18, September 1970.
Author
Dayne Hudson