Can I lose weight by eating healthy without exercise?
Short answer: Yes
Fitness is 85% diet/nutrition and 15% exercise.
If you don't go over your Total Daily Energy Expenditure then you will come out of exam period unscathed.
Proper nutrition starts with first understanding the law of energy balance, or as it's more commonly known, the rule of calories in vs. calories out:
- If you consume more calories than you burn, you'll gain weight.
- If you burn more calories than you consume, you'll lose weight.
It's that simple. To maintain a desired body fat percentage or body weight for a prolonged time, you must avoid a caloric surplus (consuming more than you burn).
No other factor has a greater impact on your body composition than energy balance.
Humans grossly underestimate the number of calories they consume.
When you eat more calories than you realize, your energy balance will be out of whack without you knowing why. This is the fastest track to spinning your wheels with fitness.
Save yourself the frustration (and years of wheel spinning) by developing and sticking to a calorie budget. It's that simple.
Basal Metabolic Rate
The first step to knowing how many calories you need is to determine your basal metabolic rate (BMR), or the minimum number of calories you need just to live.
Here's an online calculator if you need one, but the BMR equation for men looks like this:
Men's BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)
For women, the equation looks a little different:
Women's BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
I'm 37 years old, weigh 155 lbs., and my height is 69.5 inches, so my BMR = 1596.70.
Maintenance Calories and Activity Factor
Now that we have our BMR, we can use it to calculate our maintenance calories (MC). You might also see this number called your total daily energy expenditure (TDEE).
The equation for MC is dead simple: BMR x Activity Factor.
There are five activity factors to choose from:
- 1.2 = sedentary (little or no exercise)
- 1.375 = light activity (light exercise/sports 1 to 3 days per week)
- 1.55 = moderate activity (moderate exercise/sports 3 to 5 days per week)
- 1.725 = very active (hard exercise/sports 6 to 7 days per week)
- 1.9 = extra active (very hard exercise/sports 6 to 7 days per week and physical job)
These activity factors have been known to overestimate true activity, so for the purposes of determining your MC, I suggest starting with an activity factor of 1.2.
It's better to err on the side of caution if your goal is to shed body fat.
My math works out to 1596.70 x 1.2 = 1916 calories per day. Not a whole lot.
If I eat 1916 calories every day, my weight will stay the same. If my activity stays the same and I eat more calories than that, I'll gain weight; eat less and I'll lose weight.
Just knowing this one number is powerful in that gives you a broad sense of your calorie budget each day and puts you miles ahead of your peers in the gym who have never done these simple calculations.