Update 2 – How Calorie Intake Affects Body Weight, Body Fat %, Strength and Appearance

At the end of September, I published the first update on how calorie intake affected my body weight, body fat percentage and physical appearance. As promised, I now have some more data to share, a few new relationships to analyze (energy expenditure and strength) and of coarse, some more progress pictures.

Progress Since the Last Update

  • Body Weight: 152.2lbs
    • down from 152.6lbs in the last update
  • Body Fat Percentage: 5.7%
    • down from 6.0% in the last update

Progress Picture: 03 Nov 13 – 152.2 pounds- 5.7% body fat

View all progress pictures

What is this?

Awhile ago, I started tracking my calorie intake, body weight, body fat percentage and a few other pieces of data in hopes of better understanding and sharing how my body responded to different situations. I now have enough data to make a bunch of nice graphs and interpret how varying levels of calorie intake affects my body. You can read a thorough description of this project in the first update.

New Relationships – Energy Expenditure & Strength Numbers

Energy Expenditure. In the last update, I mostly compared calorie intake to my body weight and body fat percentage. Calorie intake is a major factor in weight change, but it’s only half of the equation.

The difference between how many calories you eat and burn determines changes in body weight and body fat. An increase in calorie intake can lead to weight gain, but without knowing the entire energy picture (calories eaten plus energy expended), it’s impossible to predict changes to weight.

Unfortunately, estimating how much energy I burn each day isn’t as straightforward as counting calories. Back in August I bought a Nike Fuelband. The Fuelband is an activity monitor worn on the wrist all day. In addition to measuring the number of steps you take, it also estimates how many calories you burn based on total movements. It’s not perfect, but it provides a rough estimate which is good enough for this project.

With the new energy expenditure data, I can better explain changes to my weight. Energy expenditure explains why weight went down when my calorie intake went up or why my weight went up when my calorie intake went down. The difference between calorie intake and energy expenditure is much more important than calorie intake alone.

Strength Numbers. In the last update I talked about the importance of measuring body fat. Body fat trends give you an idea of what type of weight you’re losing. Ideally, you want to lose as much body fat as possible without compromising muscle mass. Some muscle loss is inevitable when losing weight. Faster paced weight loss is associated with increased muscle loss. To keep more muscle, create a moderate calorie deficit.

Measuring body fat is one way to ensure you’re losing more fat than muscle. If body weight is coming down along with body fat percentage, you’re moving in the right direction. Unfortunately, body fat isn’t always easy to measure. Another way to measure muscle mass is indirectly through strength numbers. Strength correlates nicely with muscle mass. If you’re losing strength, you’re also losing muscle. I used my 1-repetition max lift on squats, deadlifts and bench press to measure strength and compared those numbers to my body weight.

The Awesome Graphs

Here’s the visual representation of the data. Enjoy!

(All graphs are current as of 03 Nov 2013).

Graph #1: Body Weight vs Calorie Intake & Energy Expenditure

  • Body Weight: blue line, number on the right side
  • Calorie Intake: red line, numbers on the left side
  • Energy Expenditure: green line, number on the left side

This graph illustrates the effects of calorie intake and energy expenditure on body weight. Even though my calorie intake starts to increase at the end, my energy expenditure is just as high, explaining why my weight remained relatively unchanged. Calorie intake plus energy expenditure determines changes to weight.

As I gather more energy expenditure data, I’ll have a more complete understanding of how calorie intake and physical activity affect my body weight. It’s interesting that my calorie intake over the past few weeks seems to correlate very nicely to my energy expenditure. This is happening for two main reasons:

  • 1) I can look at my energy expenditure (Nike Fuelband) throughout the day and eat more or less based on how much I’m burning. If I’m burning 3,400 calories on a given day, I allow myself to eat more than if I only burn 2,000.
  • 2) On days in which I burn more calories, my appetite increases, “forcing” me to eat more.

Graph #2: Body Weight vs. Calorie Surplus/Deficit

  • Body Weight: blue line, number on the left side
  • Calorie Surplus/Deficit: red line, numbers on the right side

This graph is similar to Graph #1 but it combines calorie intake and energy expenditure into one line. Calorie intake + energy expenditure = changes in body weight. When calorie intake is greater than energy expenditure (calorie surplus), body weight increases. When energy expenditure is greater than calorie intake (calorie deficit), body weight decreases.

This graph illustrates the difference between my calorie intake and energy expenditure. A positive number indicates a calorie surplus (more eating than burning) while a negative number indicates a calorie deficit (more burning than eating). With more data in the coming weeks, this graph will begin to provide a more meaningful insight on the most basic weight balance rule.

Graph #3: Body Fat Percentage vs. Calorie Surplus/Deficit

  • Body Fat Percentage: blue line, number on the left side
  • Calorie Surplus/Deficit: red line, numbers on the right side

This graph compares body fat percentage to my weekly calorie surplus or deficit (positive red line=surplus, negative=deficit). There are some weird, bogus and ineffective programs promising to eliminate body fat. Creating a calorie deficit (more burning than eating) and losing weight is the ONLY way to reduce body fat. Over time, this graph will illustrate how simple it is to get ripped, increase muscle tone and improve physical appearance.

Graph #4: Body Fat Percentage vs Calorie Intake

  • Body Fat Percentage: blue line, number on the right side
  • Calorie Intake: red line, numbers on the left side

This graph illustrates the relationship between calorie intake and body fat percentage. My body fat stays stable between 3100 and 3300 calories per day and decreases with a lower intake. Remember, a calorie deficit (eating less, exercising more or a combination of both) is the only way to decrease body fat.

Graph #5: Body Fat Percentage vs. Body Weight

  • Body Fat Percentage: red line, number on the right side
  • Body Weight: blue line, numbers on the left side

This graph compares body weight to body fat percentage. A lot of people try and lose fat without losing any weight. A reduction in body fat causes a reduction in body weight because body fat is a big part of overall body weight. Burning fat and losing weight require the same steps; they are two ways of describing the same process.

Graph #6: Body Weight vs. Lean Weight

  • Body Weight: blue line
  • Lean Body Weight: red line

Lean body weight is calculated by subtracting body fat from total body weight. Lean body weight is a good way to measure changes in muscle mass. When losing body fat, some muscle loss is inevitable; it’s an unfortunate side effect of losing fat.

A lot of people want to lose fat while gaining muscle. Unfortunately, those two goals are incompatible with each other. A good goal to have when losing weight is to preserve as much muscle mass as possible. Measuring body fat percentage and lean body weight ensures you’re on the right path. Losing weight too quickly results in more muscle loss than slower paced weight loss. To preserve muscle, create a smaller calorie deficit.

Absolute Strength vs. Relative Strength

There are two main ways to gauge strength numbers: absolute strength and relative strength. Absolute strength refers to the total amount of weight you lift. For example, if you can squat 200 pounds, your absolute strength is a 200 pound squat.

Relative strength is a ratio comparing the total amount of weight you lift to body weight. Relative strength ratios allow people of different body weights to compare strength numbers. Someone who weighs 300 pounds is going to be able to lift more weight than someone who weighs 150 pounds. That doesn’t necessarily mean the 300 pounder is stronger. Relative strength compares strength numbers to an individual’s body weight and allows fair comparisons between lifters. Let’s take the following example:

  • Person 1:
    • body weight: 300 pounds
    • squat: 250 pounds
  • Person 2:
    • body weight: 150 pounds
    • squat: 200 pounds

If you simply compare their absolute strengths, person 1 is stronger because their squat poundage is higher (250lbs vs. 200lbs).

Relative strength = (amount lifted) divided by (body weight).

  • Person 1’s relative strength = 250 lbs squat / 300 lbs body weight = 0.83
    • Person 1 can squat 83% of their body weight
  • Person 2’s relative strength = 200 lbs squat / 150 lbs body weight = 1.33
    • Person 2 can squat 133% of their body weight

When you compare strength relative to body weight, person 2 is stronger because they lift more compared to their body weight (133% vs. 83%). Relative strength allows you to compare strength regardless of different body weights.

Graph #7: Absolute Strength vs. Body Weight

  • Absolute Strength: red line, numbers on the left side
  • Body Weight: blue line, numbers on the right side

In this graph, absolute strength is measured by adding up the sum of my lifts (1-repetition max weight on squats, deadlift and bench press) each week. Typically, absolute strength (which is simply the sum of weight lifted) decreases with a decreasing body weight. A stable absolute strength during weight loss is a very good indicator you are losing more fat than muscle.

Graph #8: Relative Strength vs. Body Weight

  • Relative Strength: red line, numbers on the left side
  • Body Weight: blue line, numbers on the right side

This graph compares relative strength to body weight. I calculated relative strength by adding up the sum of my three lifts each week (1-repetiton max squat + 1-RM deadlift + 1-RM bench press) and dividing by body weight.

My strength numbers are somewhat atypical. I would expect to see them (both relative and absolute) go down with a decreasing body weight. When losing weight, it’s practically impossible to only lose body fat. Weight loss comes from losing body fat in addition to some muscle mass. You can take steps to minimize muscle loss, but you cannot completely eliminate it. I am not sure why I seem to be getting stronger as I lose more weight but I doubt I can keep this pace up for much longer if I continue my weight loss.

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