CARB CONTROVERSY

Low carbohydrate? High carbohydrate? Ketogenic?  Where does this carbohydrate controversy come from?  Throughout this article I will explain some key concepts related to carbohydrate intake and body composition.

I will preface this article by saying that black and white statements about nearly any fitness & health related issue is a common mistake.   Both nutrition and dietary strategies should be implemented based on your current physiology. How do we establish this? … Assessment!

An initial assessment should take into consideration all potential variables related to your goal.  For a person striving to achieve their ideal beach body, current diet, body fat and body weight all provide critical information in regards to an individualized starting point.

low carb

So, are low carbohydrate diets effective … IT DEPENDS!

What is considered a low carbohydrate diet?

If we are looking at ketogenic diets (extremely low carbohydrate diets), they will often start as low as 20g/day.  Ketogenic diets are rarely, if ever, necessary for fat loss.

The quantity of carbohydrates in your diet is highly dependent on:

  • Body composition (body fat, lean mass and total body weight)
  • Activity level
  • Current macronutrient ratios (carb:fat:protein)

Bottom line = providing a generalized recommendation is impossible, ‘low’ is really a relative term.

First, I will define a few key components related to the carbohydrate controversy.  Then I will show you where to start and how to improve compliance to a low carbohydrate diet (if necessary)!

Blood sugars: This refer to the amount of glucose (sugar/carbohydrate) present in the blood.

Insulin: is released when blood sugars are elevated, acting on skeletal muscle, liver and fat tissues allowing for glucose absorption.  In the liver and skeletal muscle glucose is stored as glycogen while in fat tissue it is stored as triglycerides.  Insulin resistance occurs when the body becomes less sensitive to insulin and therefore higher volumes of insulin are necessary to regulate blood sugars.  Increasing lean mass improves insulin sensitivity and provides more storage for carbohydrates. Consequently leaner individuals can handle more carbohydrates without experiencing increases in fat mass like their fatter counterparts. The beauty of insulin is that we have complete control through dietary and training choices.  Meals that contain large amounts of carbohydrate with high glycemic load (higher glycemic load = more significant impact on blood sugars) will result in large spikes in blood sugars and insulin secretion.  We are able to improve insulin sensitivity through low carbohydrate periods followed by a higher carbohydrate re-feeding.  The low carbohydrate period is dependant on several factors including lean mass and body fat, and this will be clarified later.  Managing blood sugars and insulin is critical to achieve optimal health.

When blood sugars regularly rise and fall fat tends to be stored around the mid section of the body (often referred to as love handles).   If your fat tends to accumulate in this pattern the low carbohydrate approach is definitely something you should consider.   In the photo below we did not use fancy supplement or diet pills but manipulated carbohydrate intake.

fat loss

Leptin decreases hunger:  Leptin in the blood stream crosses the blood-brain barrier acting on receptors in the hypothalamus (in the brain) where it decreases appetite.  The more body fat a person has the greater amount of circulating leptin, which at first glance sounds appropriate.  Search a little deeper and we’ll find that people with higher body fat percentages have more circulating triglycerides in the blood stream.  Despite the large quantity of leptin, triglycerides block passage through the blood brain barrier.   This reduced sensitivity to leptin may result in excess eating.  Studies on very low carbohydrate diets indicate substantial reductions in circulating triglycerides, this is one application for low carbohydrate diets… improve leptin sensitivity and ultimately appetite control.

Ghrelin: Hunger stimulating hormone.

GLUT4: Glucose transporter type 4 is an insulin-regulated glucose transporter found in fat and muscle.  GLUT4 increases in skeletal muscle during exercise meaning that when carbohydrates are consumed less insulin needs to be released in order to transport glucose out of the blood and into skeletal muscle.  Therefore a great time to eat the majority of carbohydrate is post workout when the body is more prepared to properly transport glucose.

Low carbohydrate diets:

*The biggest mistake when undertaking a low carbohydrate diet is cutting them out without replacing any calories with protein and fat! For many, carbohydrates make up 50-70% of their diet. If this person drops carbohydrate intake to 20 or 30% without making other macronutrient adjustments (protein, fat) this is a problem!  This will create a drastic caloric deficit. Sure this will result in weight loss, you will lose fat AND you will start to lose lean mass… progress will eventually stall and when you return to a ‘normal’ diet body fat and bodyweight will both likely increase!!!  Creating a caloric deficit is often critical but eliminating carbohydrates without making other adjustments = mistake.

So why would anyone want to follow a low carbohydrate diet?

How long should a person stay on a low carbohydrate diet?

Lower carbohydrate diets are an effective way to reduce body fat and potentially maintain lean mass provided you are consuming quality protein and fat sources. Low carbohydrate diets for extended periods of time can be counterproductive and exhausting. To avoid exhaustion or plateau here are some general guidelines regarding re-feed periods:

  • 16+% body fat, start with a re-feed every 3 weeks, higher body fat percentage = longer periods between ‘re-feed’
  • 10-15% every two weeks
  • sub 10% every 6-10 days

Re-feed days are often referred to as cheat meals, but this can be mis-leading as it may imply you are deviating from the plan.  This is not the case.  The use of re-feed (cheat) meal/day is critical to increase metabolic rate which may otherwise result in stalled progress. This does not mean that you should go out and eat pizza, ice cream and potato chips you simply need to include more carbohydrates.

How low should I start my carbohydrate intake:

Here are some carbohydrate percentages (% of total caloric intake). The number on the left indicates your current body fat and the number on the right indicates carbohydrate percentage to start with:

  • 16+ — 20-25%
  • 10-15 — 30-35%
  • sub 10 —  30-45%

This does not mean that everyone over 16% body fat starts with carbohydrates at 20% of daily caloric intake.  This is simply to give you an idea of where you may start.  With higher body fat percentages more than likely you will need to follow a diet where carbohydrates make up less of your daily caloric intake.

low carb

Now for some clear application on how to make low carbohydrate diets work for you:

Step #1:  Higher protein breakfast

Why?

Higher protein (HP) compared to higher carbohydrate (HC) breakfast demonstrate that HP breakfast results in decreased ghrelin (hunger) after the meal (postprandial) and reduced gastric emptying.  If you are consuming a high carbohydrate breakfast the speed of gastric emptying increases, and ghrelin will increase.  I don’t know about you but when I get smacked with a sudden urge to eat I am usually drawn to higher carbohydrate meals that require less preparation.  By consuming a higher protein breakfast you are setting yourself up for success in sticking to a low carbohydrate day.

In conclusion, carbohydrate intake is highly specific to your current body fat percent, lean mass, activity level and goals.  Like training, nutrition needs to be progressive and dynamic.  Low carbohydrate diets are powerful and beneficial in specific situations but are not universal.

 

 References

http://www.ncbi.nlm.nih.gov/pubmed/19793510, low carbohydrate diets: an update on current research

http://www.publicaffairs.ubc.ca/2012/12/04/ubc-research-finds-another-culprit-for-obesity-too-much-insulin/, UBC research finds another culprit for obesity: Too much insulin

http://www.ncbi.nlm.nih.gov/pubmed/8666154, relationship between insulin sensitivity and plasma leptin concentration in lean and obese men

http://diabetes.diabetesjournals.org/content/53/5/1253.full, Triglycerides induce leptin resistance at the blood-brain barrier

http://jn.nutrition.org/content/135/6/1339.full, Modification of lipoproteins by very-low carbohydrate diets

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC524355/, metabolic aspects of low carbohydrate diets and exercise

http://ajcn.nutrition.org/content/83/2/211.full, effect of high protein breakfast on the postprandial ghrelin response

http://www.tandfonline.com/doi/pdf/10.1080/02640414.2011.585473 

Categories: NUTRITION, Uncategorized

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