Update 1 – How Calorie Intake Affects Weight & Body Fat Percentage

Before smartphones and apps, counting calories was tedious. I started counting calories back in 2006 using Excel Spreadsheets. In mid-2012, I found an app called MyFitnessPal which made counting calories “fun.” Instead of using spreadsheet functions, I could simply scan a bar code, enter the serving size and let the app do the rest. MyFitnessPal allowed me to count calories more precisely, taking my diet to the next level.

In December 2012, I went back to Excel, not to count calories, but to track how my calorie intake affected my weight and body fat percentage. I finally have enough data to look back on and make some conclusions which I will share with you today.

Controlling Weight Through Calorie Balance

A common theme on this site is calorie balance. Whether you want to gain, lose or maintain weight, calorie balance is the only tool you have. The relationship between how many calories you eat and burn is the ONLY thing capable of affecting weight and body fat percentage. Over the years, counting calories has allowed me to reside within a ~15 pound range.

When I wanted to gain weight, I [verifiably] ate more. When I wanted to lose weight, I [verifiably] ate less. When I wanted to maintain my weight, I [verifiably] ate what I burned.

Verifiably counting calories means careful accounting for everything you eat – measuring cups, food scales and nutrition labels. I used food food scales very rarely as it was almost always easier to gauge serving sizes with measuring cups & spoons.

Too often, people eat multiple servings but count them as a single portion. This leads to underestimation of overall calorie intake. All you can eat chips and queso is not one, 140 calorie serving. It is very hard to fail at weight balance (gaining, losing or maintaining) when you know how many calories you burn and exactly how many calories you eat each day.

Here’s What I Did

Daily: Careful Calorie Counting. Calorie balance starts with careful calorie counting. I like MyFitnessPal but there are plenty of other apps that do the same thing. Remember, accurately counting calories with the aid of measuring cups/spoons or food scales is the only way to ensure you’re eating the appropriate amount of calories. Measuring food also helps you visualize how calorie dense junk foods really are.

For example, a 200 calorie serving of sugary food (cookies, chips, muffins, doughnuts) takes up much less volume than a 200 calorie serving of vegetables, brown rice or whole wheat pasta. The latter will do much more to keep you full for a longer period of time, and therefore decrease your daily calorie intake.

MyFitnessPal weekly calorie intakeWeekly: Averaged my Daily Calorie Intake. For the purposes of this project, I decided to graph my average calorie intake for the week (which MyFitnessPal calculates automatically – see picture to the right) rather than plot my daily intake levels.

Weekly: Weighed Myself. For this project, I only weighed myself once per week. I wasn’t interested in daily weight fluctuations. Instead I was more concerned in the general direction of my weight. For consistency, I did this every Sunday morning at the same time (after the bathroom, before breakfast).

Weekly: Body Fat Testing. Right after weighing myself, I also used a hand held body fat tester to measure my body fat percentage. This convenient and low priced gadget uses bioelectrical impedance to measure body fat. Though it might not be the most accurate measure of body fat, it is extremely easy to use, quick and inexpensive.

While the body fat percentage itself might not be accurate, I was more interested in the week to week change. At the beginning of this project, my body fat started out at ~9% and made its way down to ~6%. While I’m not 100% sure that my body fat was actually ~6%, I was fairly certain that it went down (from 9% to 6%). The exact body fat percentage isn’t as important to me as the direction of the change (down).

The Awesome Graphs

Now onto my findings. My spreadsheet currently contains five columns: date, weight, body fat percentage, lean body weight and average calorie intake.

Importance of Lean Body Weight

Lean body weight is important because it’s a measure of how much you weigh without factoring in body fat. A stable lean body weight indicates you are losing fat while preserving muscle.

During weight loss, some loss of muscle mass is inevitable. Crazy crash diets that rely on very low calorie intakes and excessive amounts of exercise can lead to fast weight loss at the expensive of muscle tissue. Keep your calorie restriction and physical activity at moderate levels to preserve muscle mass during weight loss. Losing a lot of muscle during weight loss means you’re moving too fast. A declining lean body weight indicates you need to increase your calorie intake.

(All graphs are current as of 15 Sep 2013).

Graph #1: Body Weight vs Calorie Intake

The first graph tells a simple story. It compares body weight (the blue line corresponds with the numbers on the right side of the graph) to calorie intake (the red line corresponds with the numbers on the left side of the graph).

The most basic weight balance rule is controlling your calorie intake. The difference between how many calories you burn and eat is the ONLY thing that causes weight change. A calorie deficit (burning more than you eat) causes weight loss. A calorie surplus (eating more than you burn) causes weight gain. There is no way around this simple weight balance equation; any plan that doesn’t incorporate elements of this will fail.

For the most part, an increase or decrease in my calorie intake led to a corresponding increase or decrease in my weight. This graph does not tell the complete calorie balance story as it leaves out physical activity. That can be one of the reasons why during the later stages of this graph, my calorie intake increased without a increase in weight.

If you increase your calorie intake by 200 per day, but counteract it with a corresponding increase in your physical activity level (burning 200 more calories per day), your weight will remain the same.

Graph 1: Weight vs Calorie Intake

Graph #2: Body Fat Percentage vs Calorie Intake

The second graph tells a more important story. It compares body fat percentage (the blue line corresponds with the numbers on the right) to calorie intake (the red line corresponds with the numbers on the left).

In the quest to lower body fat percentage, people do some crazy things. They use creams, perform thousands of sit ups, try weird diets (detox, low-carb, low-fat..) or waste their money on ineffective supplements. This graph illustrates the truth about burning fat: decreasing your calorie intake leads to a decrease in body fat.

My body fat was stable while I ate between 3,100 and 3,300 calories per day. It started going down only when I decreased my calorie intake. Just like my body weight, my body fat percentage closely mirrored any increase or decrease in calorie intake.

Unfortunately, there is no way to tell your body where to burn fat from (spot reducing). All you can do is create a calorie deficit (burn more calories than you eat) which starts the fat burning process.

Graph 2: Body Fat vs. Calories

Graph #3: Body Fat Percentage vs. Body Weight

The third graph compares body fat percentage (the red line corresponds with the numbers on the right) to body weight.(the blue line corresponds to the numbers on the left).

This graph illustrates that burning body fat causes a reduction in body weight. A lot of people try to “burn fat without losing weight.” This is very difficult if not impossible to do. It is very easy to lose weight. You can lose 1-2 pounds per week (4-8 pounds per month, 48-96 pounds per year). The reason you lose weight when losing fat is because it’s almost impossible to replace the weight you lose with enough muscle to counteract all the weight loss.

While losing 8 pounds per month is an achievable goal, gaining 8 pounds of muscle per month to replace the lost weight is impossible, especially if you’re in a calorie deficient state. Building muscle requires a calorie surplus – the opposite of what burning fat requires. The two goals are incompatible when attempted simultaneously.

This graph shows that when I started losing fat, my body weight also decreased.

Graph 3: Body Fat vs. Body Weight

Graph #4: Body Weight vs. Lean Weight

The fourth graph compares body weight (blue line) to lean body weight (red line).

Lean body weight is your body weight minus your body fat. For example, if a 200 pound person is 10% body fat (200lbs x 10% BF), that person is carrying 20 lbs of body fat. Their lean body weight would be (200lbs – 20lbs) 180lbs. Your lean body weight can tell you what type of weight you are losing.

When losing weight, your goal is to lose as much body fat as possible. Acquiring the means to measure body fat is the only way to measure how much fat you are burning. Hand held body fat analyzers and scales that calculate body fat are relatively cheap and easy to use.

This graph illustrates how much body fat I am burning. During this period, my highest weight was 168.6 on 28 Apr 13. That day I measured myself at 9.6% body fat with a lean weight of 152.41 (math: 168.6 x .096 = 16.19lbs of fat, 168.6 – 16.19 = 152.41lbs lean body weight). The most current data point put me at 152.6 lbs at 6% body fat (9.16 lbs of fat) with a lean body weight of 143.44.

In percentages, I cut my total body weight by 9.5%. My lean body weight decreased by 6%. Ideally, you want your lean body weight to decrease less (in terms of percentage) than your total body weight.

When you lose weight, losing muscle is inevitable. As I mentioned above, gaining muscle and burning fat have opposite requirements. One requires a calorie surplus, while the other requires a calorie deficit.

Gaining muscle is a different way of saying gaining weight, while burning fat is a different way of saying losing weight. You simply can’t gain and lose weight simultaneously.

Graph 4: Body Fat vs. Lean Body Weight

Burning Fat Without Losing Muscle

Though losing some muscle during weight loss is inevitable, you can take steps to burn through more fat and less muscle. Losing weight requires a calorie deficit: burning more calories than you eat. When you burn more than you eat you create an energy shortfall forcing your body to look to non-food energy sources, typically body fat and muscle. The larger your calorie deficit, the more your body must rely on those non-food energy sources.

You can partially mitigate muscle loss by creating a smaller calorie deficit; don’t drastically decrease your calorie intake. There is no optimal calorie deficit allowing you to burn 100% fat and 0% muscle, but eating 500 calories less than what you burn is a good starting point. Through trial and error (tracking your weight, body fat percentage and calorie intake), you will eventually start to figure out when you are burning more fat than muscle.

Slower changes typically lead to better results (in terms of appearance and staying power) than quick, drastic changes. While drastic changes result in quicker short term weight loss, the price is more muscle loss. Those short term results are also unlikely to stick with you for a long period of time because drastic changes are too hard to get used to. Slow changes allow you to adjust to your new lifestyle.

Progress Picture 1: 15 Sep 13 – 152.6 pounds- 6.0% body fatfull size

View all progress pictures

Progress picture - 15 Sep 13

The Bottom Line

Hopefully you learned about the simple relationship that exists between your calorie intake, body weight, body fat percentage and lean body weight. In the coming months, I will post regular updates so you can monitor my progress.

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