In the previous post, I explained why counting calories usually fails. In short, the most significant problem is determining how many calories you need. From my own personal experience, I determined that measuring your personal calorie requirements is best.
Methodology
Basically, exercise a consistent amount and eat the same number of calories each day over a period of time. If your weight decreases, you know that your maintenance calorie requirements are higher than what you have been eating. If your weight increases, you know that your maintenance calorie requirements are lower than what you have been eating. If your weight does not change, you have been eating your maintenance calories. That's easy, right? Well, tracking your weight presents several challenges.
The first step is to weigh yourself every day. You want to choose a consistent time, such as after you first wake up. This is important because your weight will vary significantly throughout the day. You will notice that your weight varies significantly over the course of days as well. Below is a graph of my own weight over 10 weeks and about 15 pounds of weight loss.
I read an article from a fitness coach that included similar graphs of her clients' weight data. She claimed that these "sawtooth" fluctuations were due to human willpower failing in a diet-cheat cycle. I cannot speak for her clients, but I did not cheat during this entire period of time. I counted my calories strictly every day and consistently exercised. These are natural fluctuations of my weight based upon various factors that I did not attempt to identify.
Making It Work
A healthy weight loss rate is widely considered to be two pounds or less a week. Due to these fluctuations of several pounds a week, you cannot reliably know how your weight is trending over the period of a week or two if you weigh only once a week. This is a matter of spending at least a month to determine how much you need to eat rather than spending a week or two. By weighing every day, you collect enough data to filter out the fluctuations to see the trend of your weight. This filtering is similar to a low pass filter. Being an engineer, of course I was going to bring something like signal processing into this.
If you discretize the differential equation for a simple RC low pass filter circuit, you derive the algorithm for exponential smoothing. Here is a great video that explains how exponential filtering works in practice.
In short, exponential smoothing will remove the fluctuations. However, it does not distinguish a trend from the fluctuations. When there is a trend, the trend of a filtered curve lags the trend of the data. This is not desirable when you want to reduce or increase your caloric intake as responsively as possible.
The solution to this is Holt's exponential smoothing, or double exponential smoothing. This form of smoothing includes another component to track and update the trend. Here is another great video on this form of smoothing.
My Excel Application
For my personal use, I created an Excel sheet to track all my weight measurement and apply Holt's exponential smoothing. The image below contains the raw measurement data in yellow with the smoothed curve in green. The red dashed line is the trendline of my weight around the middle of the dataset as used in the smoothing algorithm.
The raw data is mostly ignored and could even be hidden. I look to the filtered curve to know my current weight, and I use the red line to determine how quickly I am losing or gaining weight. By tracking my weight in this way, I am able to track changes in the trend to determine how my average caloric intake corresponds to my average caloric needs over time. This data helps me responsively increase or decrease my caloric intake as needed. This is particularly important because caloric needs change as your body changes.
In a later post, I may detail this tracking spreadsheet and how to actually implement the smoothing algorithm. And, it is important to note that there is more to loosing and gaining weight than just your weight. Body composition, health, and more must also be considered. Accurately determining your caloric needs is merely one element.
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