In our last article, The Psychology of Making Nutritional Changes, we reviewed basic questions one must ask themselves before making long term or perhaps challenging nutritional changes.
The reality is that nutritional strategies are more than just not eating some things or eating more of something else. Food serves social, emotional and physical needs. On the heels of physical needs, every person is different and there is no ‘one fits all’ formula. What works for one person will not necessarily work for someone else.
In consideration of the above and because you are psyched to make nutrition changes lets explore some of the basic science of making changes the elicit results.
Basic Weight Loss Science - Calories In and Calories Out
First thing you must understand is that if you eat more calories than you need in one day you will likely put on weight and/or store excess body fat. If your body only needs 2000 calories but you eat 3000 calories your body will store excess calories as fat and chances are your weight will increase.
On the other hand, if the person in the above example ate less than 2000 calories in one day, the math is more conducive to permit weight loss.
Most people have no idea just how many calories they consume or even need. Tracking your calories is one of the best ways to implement the science into your nutrition plan. You will become aware of how much you are eating which will help you make better choices and hence reach your nutrition goals.
How Many Calories Do You Need?
Everyone is different as it depends on things such as your weight, body fat percentage and how much activity you do on a daily basis. The first step is to calculate your Basal Metabolic Rate (BMR). BMR tells you how many calories (kcal) you need for your bodily functions to carry on if you were at rest one day.
BMR Calculation:
BMR (Men & Women) = 370 + (21.6 X lean mass in kg*)
*Lean mass, is your body weight minus your fat mass and can only be determined with body fat percentage analysis.
If you are a 176 lb male with a body fat % of 19% then your lean mass would be 142.6 lbs or 65 kg (176 lbs X 81%).
Therefore BMR = 370 + (21.6 X 65 kg)
BMR = 1774 kcal
Therefore this 176 lb male needs 1774 kcal for basic bodily functions to continue. Once you know BMR you must then factor in your Total Daily Energy Expenditure (TDEE). This is important because two people with a BMR of 1774 kcal but one being sedentary and the other being active will have a very different TDEE. The latter individual will require more calories than the sedentary individual and therefore have a higher TDEE.
TDEE Calculation:
TDEE = BMR X Activity Multiplier
Activity Multiplier
Sedentary = Little to no exercise, desk job = 1.2
Lightly Active = Light exercise or sports 3-5x/wk= 1.375
Moderately Active = Moderate exercise or sports 3-5x/wk = 1.55
Very Active = Hard exercise or sports 6-7x/wk = 1.725
Extremely Active = Hard exercise or sports twice a day or physical labour job = 1.9
In our above example with the 174 lb male, let’s assume he has a desk job. Therefore his Activity Multiplier would be 1.2.
TDEE = 1774 kcal X 1.2
TDEE = 2129 kcal
This shows that although he is mostly sedentary, he does walk to his office along with other basic daily activities. Once you know your TDEE, it is time to assess whether it is weight loss or weight gain you are striving for. We will continue this example as if weight loss is the goal, and therefore a deficit should be applied to the TDEE. Without applying a deficit this individual if consuming 2129 kcal a day would simply maintain their weight.
Weight Loss Deficit
What level of deficit applied to your TDEE is determined by assessing your experience and your goals. For healthy long term fat loss you should consider a conservative deficit of 15-20%.
Deficit Multipliers
Conservative deficit = 15-20%
Moderate deficit = 21-25%
Aggressive deficit = 26-30%
Extremely aggressive deficit = 31-40%
Semi-starvation = 50% or more
While more of a deficit may allow more weight loss, it may not be right for your body. An aggressive deficit will also lead to muscle mass loss therefore should be used with caution and only if you have a lot of extra body fat. That is why taking it easy at first and assessing how you feel along with monitoring your results is the best way to approach it.
Finally, with our 174 lb male desk worker example, we see his total daily calories below with the applied deficit of 15-20%.
TDEE = 2129 kcal
15% = 2129 - (2129 X .15) = 1810 kcal/day
20% = 2129 - (2129 X .20) = 1703 kcal/day
Therefore he should strive for 1703-1810 kcal/day to elicit some weight and fat loss.
Knowing and applying the above formulas to yourself is a great way to start your fat loss journey. Most people who follow the above systems and become aware of their calories will reach some level of success with their new program. Note however, that the above is just a starting point. There are more tools to learn and apply such as macronutrients which we will discuss in our next blog.
Lastly, the human body is a very complex system and there are many examples of people who do not achieve success with calorie and macronutrient adjustments alone. There could be medical or physiological issues happening that are not seen with the naked eye or solved with basic caloric adjustments. In this case, seeing a specialist for further tests would be the best step.