The Secret to Weight Loss (It’s No Big Secret!)

Patrick Gilbert PT, DPT, ATC, CSCS

Many people try to lose weight for one reason or another. They workout relentlessly and try various different approaches, but never see a change on the scale. Too many people forget one of the main principles behind losing weight: NUTRITION. You can have the absolute best exercise program in the world, but if your nutrition isn’t right for your goals, you will fail to see the results you really want, no matter how much hard work you put in at the gym.

At its core, weight loss is a math equation.

Calories In – Calories Out = Caloric/Energy Balance.

Are there other factors at play regarding weight loss? Absolutely! Genetics, hormones and so many other factors also have roles to play, but for simplicity sake, we will stick with crunching the numbers.

So what does “calories in, calories out” (CICO) mean? Let’s break it down.

“Calories In” is fairly simple; it just means what you ingest throughout the day. There are a variety of ways to calculate this, but it does involve keeping track of what you eat.

“Calories Out” is a bit more complex, and has a couple different factors at play. It involves your Basal Metabolic Rate (BMR) plus your energy expenditure from activity/exercise. Simply put, if you have a positive energy balance at the end of the day you will gain weight. Conversely, if your energy balance is a negative number, you will lose weight.

BMR is essentially the amount of calories you would burn in a day if you were completely sedentary. There are a variety of ways to calculate your BMR. For the purpose of this article, we will use an equation to approximate. I will show the equation for each gender, then apply it for two sample cases.

BMR Calculation (Harris-Benedict Equation)1

MenBMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
WomenBMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

So if you have a 22 year-old male who weighs 242 pounds (110kg) and is 6 feet tall (182.88cm)…

(10 x 110kg) + (6.25 x 182.88cm) – (5 x 22 years) + 5 = 2,138

His estimated BMR is 2,138 calories per day.

Now let’s take a 45 year-old female who weighs 165 pounds (75kg) and is 5 feet 6 inches tall (167.64cm)…

(10 x 75kg) + (6.25 x 167.64cm) – (5 x 45 years) – 161 = 1,411.75

Her estimated BMR is 1,412 calories per day.

This means that if these two individuals consume 2,138 and 1,412 calories, respectively, in one day and remain perfectly motionless, they will maintain their weight. Of course, nobody remains completely stationary through an entire day; there will always be energy expenditure on top of this BMR.

This equation uses the following “multipliers” to add to your BMR based on how physically active you are during the day:

  • BMR x1.2 – Sedentary (little/no exercise)
  • BMR x1.375 – Light (light exercise 1-3 days/week)
  • BMR x1.55 – Moderate (moderate exercise 3-5 days/week)
  • BMR x1.725 – Heavy (hard exercise 6-7 days/week)
  • BMR x1.9 – Rigorous (very difficult exercise multiple times/day)1

It is important to note that weight loss should be a consistent and gradual change, rather than a crash diet to lose as much weight as possible. It is better to shoot for losing between 0.5 and 2 pounds per week. This will help you be more consistent with your nutrition and you will actually be able to stick to your program!

For decades it was believed that one pound of bodyweight equates to approximately 3,500 calories.2 While more recent research has refuted the exact number of calories in a pound of bodyweight3, we will use this number as an approximate goal. It is easier to picture if we break this down into each day. If we are trying to lose 1 pound per week, 3,500 calories / 7 days = 500 calories/day. This means that we need to have a calorie deficit of approximately 500 calories each day in order to lose that one pound in one week.

Let’s apply this situation to our 22 year-old male whose BMR is 2,138 calories per day. If he wants to lose 1 pound in a week, his daily caloric/energy balance needs to be 1,638 (2,138-500=1,638), right? Not exactly – don’t forget about the BMR multiplier. He has a couple options to attaining this goal:

  1. First, you need to factor in the BMR multiplier, even if he were to remain sedentary and not engage in any physical activity. Under this condition (which is HIGHLY UNADVISABLE!) his estimated daily calories burned is multiplied by 1.2. Here, his BMR of 2,138 increases to 2,566. To lose one pound/week, he would need to take 500 from that number and consume about 2,066 calories/day.
  2. He can also use the BMR multiplier to re-assess his total calories needed to hit his goal with exercise. For example, if he is working out 4 days/week, he can multiply 2,138 x 1.55 to get 3,314. From there, take 500 calories from 3,314 and you are left with 2,814 daily calories.
  3. He can also forgo using the multiplier and try to determine exactly how much activity he has completed. He would then need to subtract that from his “Calories In”. For example, let’s say he completed a workout where he burned 350 calories, then took a 20 minute walk where he burned another 200 calories. He would have burned an additional 550 calories, which bumps his available “Calories In” back up to 2,038 (1,638+550=2,188). This may tend to underestimate calories burned through exercise, since even just walking and living your normal life will expend energy. It will also require more meticulous planning and logging of all exercise rather than just using the multiplier.

Under all three conditions he should be on track to lose about one pound per week. However, I will ALWAYS advise to incorporate exercise and activity into your nutrition plan to help attain your weight goals.

While we like to make things simple by using equations and math, the human body is not a calculator. As I said earlier, there are so many other factors at play when it comes to bodyweight and body composition. By starting to think about your energy balance and CICO, you are already ahead of the game in trying to take control of your weight.

My personal suggestion for keeping track of “Calories In” and “Calories Out” involves a free app/website. MyFitnessPal is an excellent tool for keeping track of your daily caloric balance. Their food database is HUGE and it learns some of your more frequent meals as you use it more. The app can automatically enter these for you if you so choose. It can determine a rough estimate of your BMR and set that as your total caloric goal each day, depending on your weight loss/gain goals. You can set your “Activity Level” as “Not Very Active”, “Lightly Active”, “Active” and “Very Active”. This will factor in your activity level and modify your BMR accordingly, so you don’t have to do the math. There is also a section where you can input activity completed for the day. Of course, the calories burned for certain activities are not completely accurate, as they are based on an average, not you as an individual. But it is pretty darn good for a free app!

So choose whatever platform you desire and get started!

Disclaimer: I receive no financial compensation from MyFitnessPal. It is simply a personal recommendation that I, along with many others have had success with.


  2. Bortz WM. Predictability of Weight Loss. JAMA. 1968;204(2): 101–105.
  3. Thomas DM, Martin CK, Lettieri S et al. Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule. Int J Obes. 2013;37: 1611-1613.

About the Author – Patrick Gilbert PT, DPT, ATC, CSCS


Patrick is a physical therapist, athletic trainer and personal trainer. He runs Summit Performance and Therapy in Indianapolis, Indiana. He has been training clients of all backgrounds for years and has been a practicing physical therapist since 2016. His training philosophy combines his knowledge of rehabilitation as well as strength and conditioning in order to train clients to achieve great results and avoid injuries in the process. His physical therapy practice focuses on a three-dimensional view and treatment of the body and its many parts. Treatment emphasizes manual techniques and rehabilitative exercises to get patients back to previous activity levels without pain or dysfunction.

For more information about training or rehabilitating with Patrick, contact him at or visit

2 thoughts on “The Secret to Weight Loss (It’s No Big Secret!)”

Leave a Reply