How Much Carbohydrate Do You Need?

Carbohydrate

And so we come to Carbs; probably the most divisive of the macronutrients. People seem to either love them or hate them, indulge in them or attempt to totally exclude them. As with most extremes, the truth is somewhere in between.

Carbohydrates are the bodies preferred energy source and a vehicle for fibre and micronutrients. Let us not also forget the fact that they are god damn tasty.

All Carbohydrates (apart from fibre) are broken down into one of three sugar molecules;

  • Glucose
  • Fructose
  • Galactose

These are what you may hear referred to as Simple Carbohydrates or Monosaccharides; meaning they only contain one sugar molecule. We also refer to Disaccharides (two sugar molecules) as Simple Carbohydrates; they are made by combining more than one monosaccharide.

  • Lactose = Glucose + Galactose
  • Sucrose = Glucose + Fructose
  • Maltose = Glucose + Glucose

Complex Carbohydrates are just longer chains of sugar molecules called Polysaccharides. 

Keep in mind that whatever the source of Carbohydrate, be that rice, bread, pasta, skittles, goji berries, doughnuts or whatever, they will be broken down into the same constituent parts; glucose, fructose and galactose. 

The ratio of complex to simple sugars affects how quickly they are broken down and absorbed by the body. Slower rates of digestion tend to make us feel fuller and provide a more continual drip feed of energy. However the speed of digestion is compounded by:

  • Macronutrient composition of the meal
  • Total amount eaten

For example, once fat reaches your small intestine it slows the rate of emptying from the stomach by inhibiting your churning mechanism until the fat has been absorbed. You can also imagine that eating one small bite of a burger takes a lot less time to digest than the entire thing plus fries. 

And so it is too simple to say that simple sugars should be avoided. Bear in mind that most of the sugar within fruit is simple but there aren't too many people advocating the avoidance of apples. 

This may be because fruits and vegetables, while being sources of simple sugars are also great sources of fibre and micronutrients; both of which we need to be healthy. They also happen to have quite a lot of water within them so although they have simple sugars, they aren't as concentrated.

If you imagine pouring a small bit of squash into a bathtub full of water you aren't going to see the colour change but if you were to pour that same amount into a small glass...

It's the same reason your pee is clear when you're well hydrated, distillation.

And that brings us to the issue we can take with the demonisation of simple sugars, often seen in the use of the Glycemic Index (GI).

If you aren't familiar with the Glycemic Index, it is a ranking system from 0 - 100 that measures how long it takes food to increase your blood sugar levels. The problem when using it as an important method for weight loss is that it fails to account for the total amount of the sugars found within the food and tells us nothing about the total caloric content either.

For example Watermelon has a GI of 72 whereas a Snickers bar only has a GI of 51. The problem is that this doesn't begin to tell us anywhere near the whole picture: 

53G SERVING OF SNICKERS

250 Calories
4g of Protein
12g of Fat
33g of Carbohydrate

53G SERVING OF WATERMELON

16 Calories
0.3g of Protein
0.1g of Fat

4.2g of Carbohydrate


In other words to get the same number of calories as the 53g of Snickers you would need to eat 830g of Watermelon!


ENTER THE GLYCEMIC LOAD

Glycemic Load takes into account the amount of carbohydrate contained within a food with the food's ability to raise blood sugar levels
Glycemic Load = (Glycemic Index/100) x Net Carbs*
*Net Carbs = Total Carbohydrate minus Fibre

A GL below 10 is considered low
A GL above 20 is considered high

A better use of your efforts may be to focus on consuming most of your Carbohydrates from foods with a Glycemic Load lower than 20. This will tend to allow you to eat more total food, possibly feel fuller and thus more likely to stick to your diet.

So let's show you how to compare the Glycemic Load of 150g from two different Carbohydrates...you know, in case you don't want to just google it.

TOM HAS WHITE RICE

GI of 85
42.9g of Carbohydrate
0.5g is Fibre
Net Carb of 42.4

(85/100) x 42.4 = 36.04
Glycemic Load of 36.04

GEMMA HAS STRAWBERRIES

GI of 40
7.1g of Carbohydrate
2.4g is Fibre
Net Carb of 4.7

(40/100) x 4.7 = 1.88
Glycemic Load of 1.88

150G OF STRAWBERRIES

48 Calories
1g of Protein

0.5g of Fat
11.5g of Carbohydrate

150G OF WHITE RICE

195 Calories
3.6g of Protein

0.3g of Fat
42.9g of Carbohydrate


Choosing Lower Glycemic Load Food Tends To Allow You To Eat More For Your Calories

You could have 610g of Strawberries for the equivalent caloric content of the 150g of White Rice. Or just over four times the amount of food. This is the same as the Snickers versus Watermelon comparison. 

Now please note, I am not saying that there is no place for "Junk Calories" or that you should only choose fruits and vegetables for your carbohydrate allowance. Actually far from it. If you've ever spoken to me you will know that I harbour a deep love for almost all sweet things.

I think it is sensible to ensure that you have an adequate fruit and vegetable intake within your carbohydrate allotment first. This is to make sure you do not become deficient in vitamins & minerals as well as consuming a decent amount of phytochemicals. But after that I think it is a trade off between two things:

  1. Food Volume (to stay as full as possible)
  2. Glycogen Replenishment

We've spoken about Food Volume so let's talk about replacing Muscle Glycogen

MUSCLE FUEL BIOLOGY

When you contract a Muscle, especially under high intensity conditions such as weight training, you utilise stored glucose (which is called glycogen). If you do enough training or your don't fully replace the amount used (as in a diet) you will deplete your glycogen stores. At this point your gym performance begins to suffer. And as one of our aims to ensure Fat Loss without Muscle Loss, making sure we train correctly is probably the most thing we can do. 

As glycogen is stored glucose, this means we cannot use fructose, galactose or fibre for glycogen replenishment.

Fruits and vegetables do contain glucose, which will help contribute to glycogen replenishment but they also contain lots of fibre, which won't. Fruit also contains larger (a relative term here as the total quantity is still not high) amounts of fructose which also will not. 

As such there may be a time to focus on Simple Carbohydrates with a high ratio of glucose, it is just that in reality, for most people most of the time, this isn't an issue.

DIFFERENT NEEDS

  • Fructose and glucose have different transport molecules in the gut which means that a combination of fructose and glucose enables faster absorption than either one alone. Fructose will be used to replenish Liver Glycogen which allows the glucose consumed to replenish muscle glycogen.
  • An endurance athlete who needs to replenish as much glycogen as possible while racing needs to be able to re-synthesise glucose quickly and this is best achieved with a combination of fructose and glucose.
  • A dieted strength athlete is much less concerned with the speed of replenishment provided the amount consumed replaces the amount used before the next session. Note - there may be a use for periodic re-feeding due to the additive continual partial depletion of glycogen. I'll cover this in more detail in the future.

In a practical sense for most people it's unlikely that this is something that needs to be worried about. But if you're trying to get very lean or you're a competitive athlete then the type of carbohydrate you consume may be something to consider in a little more detail. For the rest of you just remember the recommendation that focusing on calories, protein and a few servings of fruits and vegetables will be all that really matters.

I am aware that some of this may seem quite complicated, all I would say is please remember the importance of context; that overly simplistic answers to questions, especially when presented as binary this-or-that straw-man arguments may not be right. And though they are often appealing and easier to accept, as they require less understanding and nuance of the topic at hand, the blind acceptance of them can lead you quite deeply down the wrong rabbit-hole, resulting in a rather large waste of your time and effort.

Take Home Point

Focus on consuming enough carbohydrate to fuel gym performance whilst at the same time respecting total calories and protein and fat targets is the aim.
It is a balancing act and it is the most variable of the macronutrient targets as a result.
Your remaining calories, after taking out protein and fat will come from carbohydrates.


EXAMPLE 1

TOM HAS 2850 CALORIES PER DAY
Fat is set at 30% of his calories
Giving him 95g (855 calories)
Protein is set at 2.5g/kg/lbm
Giving him 180g (722 calories)
Add Protein & Fat Together
(855 + 722 = 1577)
Take those away from the total calories
(2850-1577 = 1273)
Tom has 1273 calories left for Carbohydrate
(1273/4 = 318)
318g of Carbohydrate

 

EXAMPLE 2

GEMMA HAS 1450 CALORIES PER DAY
Fat is set at 15% of her calories
Giving her 24g (218 calories)
Protein is set at 2.4g/kg/lbm
Giving her 121g (484 calories)
Add Protein & Fat Together
(218 + 484 = 702)
Take those away from the total calories
(1450-702 = 748)
Gemma has 748 calories left for Carbohydrate
(748/4 = 187g)
187g of Carbohydrate

Paul StandellComment