Sunday, February 19, 2012

Macronutrient Ratios

macroSo the other week I dutifully determined my goal calorie allowance based on my lean body mass and activity level.  I’ve decided on 1500 calories for when I am exercising, 1300 when not.  But where are those calories coming from?  Should I be scoffing down chocolates, eggs, bananas, lettuce, or pasta and bread?  To work that out, I am calculating a base macronutrient ratio to start out from, with the intent to adjust it based on my results!

So I guess the first thing to ask is “What are the macronutrients and what do they do?”.  I went off to do a bit of research and this is what I have come up with..

1. Protein:  Protein is what we normally associate with animal products, but we can also get protein from vegetable sources such as grains, nuts, and legumes.  We need protein for the amino acids (proteins are all made up from different combinations of any of 22 amino acids) some of which are essential as our own bodies cannot make them, and some non-essential.  These amino acids are then used to make the proteins that we need for bodies.. from DNA through to enzymes and of course.. our muscles.  When our glycogen stores are low, protein is also utilized in the gluconeogenesis cycle.  This is especially relevant to those on low calorie diets – if our glycogen stores are low our body will utilise our protein (read: muscle) to make the glycogen/glucose that we NEED.  Then with less muscle, we need less energy so a balance is eventually restored (i.e. our BMR drops even lower).  Protein that we eat and don’t use is not stored so will be excreted meaning we need a steady intake of protein if we want to grow our muscles!

2. Carbohydrates: Nearly every eating plan/diet that is currently available is telling us just how evil carbohydrates are.  The only way to lose weight is to reduce your energy intake and carbs equals energy.. ergo – cut the carbs.  Now, while I am will happily admit that most people eat way too many carbs (put down that packet of chips!), carbs are hardly the enemy.  We need carbs, and lots of them.  They should make up most of our diet – at least 50% even in people who are carb sensitive!  There are two major types of carbs:  the sugars, which are the immediately useable form of energy (like glucose), and the complex carbs, which are the stored form of energy (including glycogen).  When we eat carbs they are first digested into simple sugars like glucose and then released into the blood stream.  At its most basic.. our metabolism is based on the oxidation of glucose releasing ATP (glycolysis) which drives cellular reactions in our bodies so it is important that our glucose levels are maintained – and that is what insulin does. Homeostasis is maintained as glucose is converted to glycogen and then back then again as needed to maintain that blood sugar level.  It is notable though, that glycogen stores in muscles do not get released back into the blood stream, but rather only used for fuelling our muscles!  Our dietary goal should be to assist that glucose homeostasis making it as easy to maintain as possible.  A steady intake of carbs throughout the day, released slowly, and taking into account any major use of our glucose stores such as exercise.

3. Fat: We have learnt a lot about fats in recent years and low fat diets are not so popular even though low fat products are!  We are more aware of the existence of ‘good’ fats and ‘bad’ fats and are encouraged to get our fats from good sources such as oily fish, legumes and nuts.  Animal fats are considered bad as they are generally the ‘trans’ fats, and most people are aware of the ‘hydrogenated vegetable oil’ as the hidden trans fat (nutella people!).  So human logic, being what it is, decides that reducing our fat intake should reduce our own fat.. right?   Wrong.. like everything else, fat is broken down through our digestive process into its base form – fatty acids. These are a lot more efficient at providing ATP and the ultimate in energy storage so provided we only consume enough fat so that it is utilized instead of stored it is a very efficient way to get energy. We need our fat, we need to have energy stored to maintain a healthy hormone balance (especially women), we need to have energy stored in case of illness, or if we are planning on running a marathon!  We need fats to digest certain nutrients, to make hormones and at its most basic, to build the very walls of our cells!  By consuming ‘healthy’ fats we are also helping our body to ‘clean-up’ the stuff that clogs our arteries!


So what are our goals with our nutrition?  We want to, in some small way, use our intake to manipulate our metabolism into using our fat stores AND still provide enough glucose to support our daily activity so as to not resort to using our muscles as an energy source.  For some people however, the goal is to maintain a low body fat percent while still providing the energy and protein requirements for muscle growth. With both these goals, the first step is the look at your total calorie intake, which I have already done.  A goal of weight-loss means that I need to reduce my calories by about 10-20% of my daily requirements giving me a goal of 1500 calories.  But all calories are not equal – I need to look at maximising the benefits of those calories to ensure my nutrition supports my goals!

There is no magic macronutrient ratio that is going to work for everybody and every goal so the first thing we need to look at is just simply getting a good balanced ratio which we can then work on based on how our own body reacts to it.  I’ve done some reading and it seems that a good starting point is a basic 50-55% carbohydrates; 30% protein; and 15-20% fat.

ARgh.. but what does that mean?  I hear you all shout.  That’s right.. it is time for the math!

To make simple, I will work with 50:30:20 and use my 50% as my minimum carbs, and 20% as my max fat.

My calories = 1500, divide by a hundred = 15

  • Carbs = 50 x 15 = 750 calories (55% would be 825 cals)
  • Protein = 30 x 15 = 450 calories
  • Fat = 20 x 15 = 300 calories (15% would be 225 cals)

Again I hear “argh.. what does THAT mean?’ so to put it into useful terms we need to know how many grams of each macronutrient we need each day to meet our calorie requirement.  The general conversion is that

  • 1g of Carbs = 4 calories
  • 1g of Protein = 4 calories
  • 1g of Fat = 9 calories

Therefore, for my 1500 calories I should be able to get (rounded):

  • 210-190g of carbs
  • 110g of protein
  • 25-30g of fat

I’ve entered these nutrient targets into calorie king and will see how I go adjust my diet to fit!  My other nutrient related goals are:

  • to include fibrous carb sources at each meal, particularly later meals
  • to have 5 meals of around 250-300 calories throughout the day
  • to always have both protein and carb together!

I will start looking at recipes that fit those goals as well, 250-300 calories with 42g of carbs, 22g of protein, and 5g of fat!  It feels so good to have a number target!



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