Controlling your weight comes down to one simple idea:
Calories in < calories burned = weight loss.
Most of the time, it really is that simple. The hard part is figuring out exactly how many calories your body burns, so that you can adjust your diet appropriately. Luckily, there is an easy way to estimate so you can get started.
There are two important numbers when it comes to calorie burn: your resting metabolic rate (RMR), and your total daily energy expenditure (TDEE).
Resting Metabolic Rate (RMR)
Your RMR is the amount of calories your body burns at rest, or your daily expenditure without exercise. When you get in a routine and build up muscle, your metabolic rate will increase. TDEE includes calories typically burned when including your lifestyle and/or exercise routine.
Calculate your resting metabolic rate:
RMR = Weight (lbs) x 10
Ex) I weigh 125 lbs, so my RMR is about 1250 calories
Total Daily Energy Expenditure (TDEE)
Calculate your total daily expenditure. Using the table below, find what activity factor most describes your lifestyle. It is important to be honest with yourself, as this factor will only be a good estimate if you are actually as active as you estimate.
TDEE = RMR x Activity Factor
|Sedentary||Most of the day seated or standing, lots of driving, no intense activity||1.3|
|Low Active||Sedentary lifestyle plus 30 min moderate activity (ex: office worker with moderate exercise)||1.6|
|Active||Low active lifestyle plus 3 hours more vigorous activity||1.7|
|Heavily Active||Vigorous activity, professional athletes, hard-labor professions||2.0|
Ex) I have a desk job, but I go to the gym for about 30-45 min 5-6 days a week.
TDEE = 1250 calories x 1.6 = 2000 calories
The third and final step of determining how many calories you should be consuming is defining what your goal is. If you aim for the higher end of the percentage change, your diet and potential body compositional changes will be more aggressive, but will also require more discipline. So, be sure to choose a path that you believe you can commit to.
Weight Loss: Decrease by 15-20%
Weight Gain: Increase calorie intake by 5-15%
Maintenance: Same as TDEE
Keep in mind that a healthy weight loss or weight gain goal is usually 1-2 lbs per week. This may not be what you wanted to hear, but it is the best way to prevent reverse effects once you adjust your diet again, such as putting any weight you lost, back on. Use this information to give yourself a realistic date to achieve your goal.
For more information on what those calories should consist of, read this post!