Welcome to the 3rd week of the Optimal Nutrition for Health, Performance and Body Composition course. Thanks to everyone that took the time to email me or add comments regarding their specific food diaries.
This week is all about applying some scientific measurement to your health and dietary goals, and how we can use this information to assist you to maintain, lose or gain weight. Diet is, for most people, total guesswork. Therefore, knowing how much you should be eating (even if it's a rough estimate) and what you should be eating puts you in a better position to be able to achieve what you want.
What is basal metabolic rate? Put simply, it's how much energy your body needs to perform its vital daily functions, assuming that you're at rest. In that sense it is the minimum amount of energy required on a daily basis. I'm hoping that you don't rest for 24 hours per day, which means that any activity you do requires additional energy over and above your basal metabolic rate (or BMR).
The guys at Bodybuilding.com have an easy to use calculator for working out your BMR, click here to visit Bodybuilding.com
Unsurprisingly, your age and weight have a big impact on BMR. Knowing this figure is important because it gives you a baseline with which to chart your daily calorie intake.
Once you know your BMR you can apply some proper planning to your daily and weekly food and fluid intake. For example, a 5 ft 10 inch male who is 35 years years old and weighs 92kg has a BMR of approximately 2000 kcal (that's me, by the way). So I know that I need to consume that on a daily basis, at least, if I want to maintain a consistent bodyweight. The reality of course is that I'm pretty active so I'll need to account for the additional calories required for that.
At this stage, it's worth clarifying what happens when your body doesn't get enough calories (in the simplest terms I can manage). It's a common misconception that body fat is fat that you ate and your body stuck it somewhere. This isn't necessarily the case. When we consume more calories than we need (and that can be from any source at all) our body decides to convert it to fat and store it for later use. Fat is, after all, a great source of stored energy that we can call on in the future when we don't have food readily available.
So when there isn't enough food available (or I decide to not eat, for whatever reason) my body will start to utilise that stored body fat for energy. That is, in a nutshell, what happens when we talk about losing weight. You'll see then that BMR is very important in being able to work out how many calories we need to consume if we want to:
That is an incredibly simplified version of what happens, but I hope the concept makes sense. It is, at the very least, a great basis with which to plan your dietary needs.
Allowing for your additional calorific needs in terms of exercise and activity can be complex but the Physical Activity Level calculation is another good starting point. It defines people as:
The number next to each activity level above is used in conjunction with your BMR to ascertain your daily calorie needs. So, in my particular example I would say that training days and days where I am particularly active would require a calorie intake of approximately 3400 kcal. Here's the example:
BMR x PAL = 2000 x 1.7 = 3400
If I want to lose weight then I need to consume less than that. If I want to gain weight then I need to consume more than that. Your task now is to assign a daily calorie intake based on the activity for that particular day. If you have a regular routine with regards to work, daily activity and training then this is pretty simple. Try this for a week and let me know how you get on in the comments below.
See you next week!