How many calories do you need daily to live? have you ever asked yourself that question? We talk about eating healthy, reducing portion sizes, cutting back on XYZ foods or food group however, how do we know if those tactics will work if we don’t know what we need in the 1st place. Understanding how our body uses calories and how much is needed for daily functions like breathing, thinking, walking and even eating is a step in the right direction to figuring out what our daily calorie intake should be.
Before we go into how we make these determinations lets examine the issue of weight, BMI and body fat. If you are determining your fitness by what the scale says and your BMI calculation you will never know your fitness level. According to BMI stats Dwayne “The Rock” Johnson is obese. According to our government standards Dwayne’s height and weight equals 34.4 which is classified as obese and his Fast & Furious costar Vin Diesel is overweight at 27.1. There are flaws in determining health based on height and weight without considering body fat to lean mass. Using our nation’s BMI Calculator a guy who’s 5-foot-10 is underweight at 130 pounds, overweight at 175, obese at 210, and extremely obese north of 275.
BMI can’t distinguish between fat and lean tissue. Nor can it distinguish between different types of fat and that is why you shouldn’t use the scale and BMI as the final determination for your fitness level and base your nutritional goals off of them. When the study looked specifically at men with a BMI of 25—the cutoff line for overweight—it found their body-fat percentages ranged from 14 to 35 percent. A person with 15% body fat is a lot leaner and probably healthier than a person with 30% body fat.
You probably realized by now that in order to understand our fitness we have to know our body fat percentage. Once you know your body fat percentage you can calculate your lean body mass and calculate how many calories you need on a daily basis. This information is crucial to know in order to design a successful nutrition plan to help you meet your goal(s). Ideally if you are looking to reduce your weight you should focus on reducing your body fat percentage instead of weight reduction.
How Do We Measure Body Fat?
Finding your body fat percentage may mean a trip to your doctor as there are several tools to measure this, such as calipers, infrared detectors, and underwater weighing. Underwater weighing is the most accurate, but it is also the most time-consuming and expensive. Calipers are the most economical and provide somewhat accurate measurements. Obese people with 30% or higher body fat will not get an accurate percentage, because the calipers will only pinch one roll of fat. I opted to purchase a body fat analyzer on Amazon that has high recommendations. The body fat analyzer gives me my body fat percentage and BMI. When setting it up it asks for my current weight and height for BMI but I ignore the BMI as I am focused on reducing body fat.
Determining My Daily Calories
Next let’s understand how our metabolism specifically basal metabolic rate or BMR plays a role in our daily calorie needs. BMR (basal metabolic rate) or RMR (resting metabolic rate) is the amount of energy expended to support the ongoing metabolic work of the body’s cells. Maintenance of body temperature, heartbeat, and respiration are continuous processes that expend energy. The energy needs for these processes must be met before any calories can be used for physical activity or food digestion. This typically accounts for about 60-70% of the body’s energy supply. For example, a person who requires 2000 calories a day will expend as many as 1200-1400 of them to support the RMR. A person’s RMR can be influenced by a number of factors, including age, height, gender, environmental temperature, exercise, and diet.
Here’s where the problem occurs. Let’s say you eat 2,000 calories a day and we’ve determined that your BMR needs are 1,400 calories a day. You went running and used 1,ooo calories for that singular activity. Did your body get the minimum amount of calories needed for the day? Here’s an opposite scenario. Same BMR needs and you went running and used 2,500 calories on your long run and because you expended a large chunk of calories you 5,000 calories for the day. Did you over consume your calorie needs for the day?
Using myself as an example I will detail how I determine my daily calorie needs. I determine my daily calorie needs by what it takes to fuel my Lean Body Mass (LBM). My LBM consist of my organs, muscles, bones the systems that keep me alive and they all need fuel or my BMR. In order to determine my LBM I have to separate it from my fat percentage.
My body fat percentage this morning is 21.6%. Next I calculate how much that my stored fat weighs Here’s the formula:
Current weight __________ lbs × __________% body fat = __________ lbs for me that 223lbs current weight X .216 = 48.17lbs of body fat that I am carrying around.
Now I can calculate my Lean Body Mass by using this formula:
Current weight __________ lbs – fat lbs. For me that is 223 – 48.17 = 174.83 of Lean Body Mass (LBM).
The next step is determining how many calories does it take to fuel y0ur LBM. Men need 13 calories for each pound of LBM and women need 12 calories for each pound of LBM to determine RMR. For me that is 174.83 X 13 = 2,273 calories I need for RMR. We use a “lifestyle multiplier” that does not include workouts to determine BMR.
- Light office work, mostly seated………………1.2
- Housework, including shopping, errands…..1.3
- Clerical, on feet most of the day doing light work …1.4
- Light construction, or lots of walking ………1.5
- Heavy construction, warehousing, moving, etc….1.6
Adding it all up
To live each day without working out and keep my organs, muscles etc. working I need to consume 2,273 calories. Now in order for me to accomplish my daily work I have multiple that by my lifestyle and I get 2,728 calories. It seems like a lot of calories and often I wouldn’t want to consume that many calories. However, if we go back to my earlier question and say I only eat 2,000 calories and I go running and burn 700 calories did I eat enough calories to sustain my body? No I am not and my body’s defense is to catabolize those needed calories from my muscles and begin the process of storing more of the calories I consume to fat to protect from starvation providing me less and less calories for fuel. It’s a mad cycle. The goal is to design eating plan can be designed based on daily caloric need. The amount of calories and the stored fat should cover all caloric needs throughout the day.
- Determine your body fat percentage and focus on achieving a good body fat percentage
- Don’t focus on weight or your BMI as they are not accurate and can lead to a false sense of fitness
- Calculate your daily calorie need so you are eating enough to have energy to train and live.
- Consume as many calories from good foods. Eliminate as much processed foods as possible
- Balance your calorie intake to include a percentage of fats, proteins and carbohydrates.
Here’s to happy & healthy running.