Many people have asked me how to calculate how much to eat and exercise to lose weight. While I won't pretend to know all the answers, I can share with you a bit of my education these last 6 months through Sharp Weight Management.
From a strictly mathematical standpoint, weight loss boils down to calories in vs calories out. Calories in would be what you eat/drink. Calories out is the amount of calories your body burns to keep your body functioning normally plus an additional exercise you do above that.
You should also know that to lose one pound, you need to burn 3500 calories. So let's break this down. I'll use a 200 lb female as my example to keep the numbers nice and neat.
The first thing you need to figure out is your Calories Out. How much does your body burn to maintain your current weight?
For women: Current Weight x 10; for Men: Current Weight x 12.
So for a 200lb women to maintain her weight she would need to net 2000 calories per day. 200 x 10 = 2000
So let's say you wanted to lose 2 lbs per week. We know that it takes a 3500 calorie deficit to lose one lb so to lose 2 lbs, you would require a 7000 calorie deficit. 3500 x 2 = 7000.
So weekly the women above eats 14000 calories.
To lose 2 lbs, she needs to cut her calories. 14000 - 7000 = 7000; 7000 / 7 = 1000 calories net per day.
The minimum calories on a non medically-supervised plan is 1200 so in order for this women to lose 2lbs per week safely, she would also need to incorporate some exercise into her plan. A min of 200 calories.
So this woman would need to consume a minimum1200 calories of food, plus burn 200 calories in exercise per day to lose 2 lbs per week. Now the more you exercise, the greater your food allowance can be. You also need to consider that the first 2 weeks on a diet is your body getting rid of excess water and toxins so you may see a temporary increase in weight loss the first few weeks.
Here is what her numbers would look like:
200 x 10 = 2000 x 7 = 14000 calories out to maintain
3500 x 2 = 7000 (desired weight loss of 2 lbs per week)
14000 + 2000 (exercise calories burned in a week) = 16000 - 7000 = 9000 / 7 days = 1285
So this woman's plan would be to consume 1285 calories plus exercise 285 calories per day. If she does not plan to workout every day, her weekly totals still need to come to 2000 to hit her 2 lbs per week goal.
One thing may people need to remember is that as you lose weight, these numbers will constantly change.
So in my case, my numbers in January looked like this:
240 x 10 = 2400 x 7 = 16800
3500 x 3.5 lbs per week = 12250
16800 + 2000 (exercise) = 18800 - 12250 = 6550 / 7 = 935 calories net per day.
Keep in mind that I am medically supervised so my calorie intake was severely reduced, I had blood work done all the time and was monitored weekly so do not do this without supervision!!
Today my numbers have changed and you will see that to keep up my momentum, I've had to increase my exercise...
165 x 10 = 1650 x 7 = 11550 weekly calories out
3500 x 2 lbs per week = 7000 (notice that I don't have the calories available to lose as much as I did when I started!!)
11550 + 3000 (exercise) = 14550 - 7000 = 7550 / 7 = 1078 daily calories in (medically supervised)
Another thing to keep in mind that while the numbers are close, the body is not as predictable. Hormones, medication, sore muscles, weather, over estimating your exercise or under estimating your food intake all contribute to swaying these numbers. But it should give you a place to start planning your weight loss.
You can also use these calculations to anticipate what it will take to maintain your goal weight in the future. For example, my goal weight is 150 lbs. So once I reach that goal, I would need to exercise and consume the following per day.
150 x 10 = 1500 x 7 = 10500 calories per week to maintain.
10500 + 2500 (weekly exercise) = 13000 / 7 = 1850 (wow that's a lot of food!)
I hope this was helpful to you. Before starting any program, speak with your doctor and work with them on your weight loss goals. It was the best thing I ever did!
Good luck!
