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Basal Metabolic Rate & Calories for Weight Loss

How many calories do you need per day?

The recommended calorie intake based on food labels and government recommendations is 2,000 to 2,500 calories per day. However, your calorie intake or calories needed a day should be a unique number. This is based on your weight, activity level and a number of other factors. 

There are some equations or estimations that can help you determine how many calories needed per day. A recent meta-analysis (a study of studies) reported that the Harris-Benedict was the most precise for people that were overweight or obese. 

For males the formula is 

  • BMR = 66.473 + ( 13.7516 × weight in kg ) + ( 5.0033 × height in cm ) – ( 6.755 × age in years )

For females the formula is: 

  • BMR = 655.0955 + ( 9.5634 × weight in kg ) + ( 1.8496 × height in cm ) – ( 4.6756 × age in years )

Calories needed without exercise or activity 

Your basal metabolic rate is the amount of calories you need per day for a normal functioning body. 

However, your body requires more calories per day if you are active- even in the slightest way. This is where Activity Factors are used. 

These numbers are typically 1.1 to 1.9 per day, depending upon activity level.

The Energy Balance Equation - IDEA Health & Fitness Association

This all seems a bit technical, so let’s use an example: 

 

Let’s say my basal metabolic rate is 2,350 calories and I complete moderate intensity exercise 3-5 times per week. 

According to the blue chart above my activity factor is 1.550.

I need to take my basal metabolic rate and multiply it by the physical activity factor 

2,350 x 1.550 = 3,642.50

This means I need 3,642 calories per day to maintain my current body weight. 

Calories needed to lose weight

It is generally accepted that you need to burn 3,500 calories to lose 1lb of body fat or 454 grams. This can be accomplished in two ways or a combination of both. 

The first is reducing calorie intake through your diet. This is intentionally keeping what is called a calorie deficit. And now it’s a simple math game. 

You want to lose 1lb per week? Then you need to be in a consistent calorie deficit throughout the week. 

Exercise can also be used to aid in a weekly calorie deficit. However, it is not the most efficient way. 

We typically recommend getting to a calorie deficit from 50% of food intake and 50% from exercise. 

This means a reduction in around 250 calories per day while also engaging in exercise that should burn at least 250 calories also. 

We know from fitness trackers that the average client at Motiv8 Fitness will burn 300 to 400 calories per workout. Let’s use 400 calories for this example. 

This means that if you were to exercise three times per week you should expect to burn around 1,200 calories. 

This puts a dent into the estimated 3,500 calories needed to reduce weight by 1lb. Yet, in this example you need to account for another 2,200 calories throughout the week. 

You could reduce your average calorie intake by 314 calories per day and you should start to see sustainable long-term weight loss.

You can aim to lose more than 1lb per week if you desire. A good rule of thumb is to aim for half a percent (0.5%)  up to 1% of your total body weight each week. 

For example- if you want to lose 7kg (15.4lbs) you can use your newly found knowledge to create a real and sustainable timeline. 

  • Current weight = 72kg 
  • Goal weight =  65kg 
  • Weight loss per week =  0.36kg to  0.72kg
  • Goal time frame = 19.44 to 9.72 weeks
  • Simple goal: lose 7kg in 10 to 20 weeks  

Summary

Losing weight can be a difficult task for a lot of people. Setting realistic timelines, determining how to create a calorie deficit and staying consistent week to week will get you in the right direction.  

While we understand the frustration of not being able to lose weight quick enough- it is worth remembering that you probably didn’t gain weight overnight. Take it slow, keep it sustainable and lose weight while building healthy long-term habits that you feel like you can maintain for the rest of your life. It will be worth it.

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