The Physics Diet


Happy holidays and post-holidays!


This is an “and more” post to help people combat post-holiday funk and guilt about over-eating and drinking during the season.   Many people have New Year’s resolutions which involve losing weight, either weight gained over the holidays or because they feel the general need for weight loss. I’m writing this post and a few others to give some practical advice for those in need, and to look at the science (physics, particularly) of dieting and weight loss. This is going to be the first in three or four posts on the general subjects of dieting, exercise and weight loss, including a literary and philosophical discussion of one’s ideal weight.

I feel that I can write with some authority on this. Between April 2012 and April 2013, I lost 50 lbs, going from an initial weight of 205 lbs to a final weight of 155 lbs. More to the point, I have kept my weight at this level since then. I’ve included a graph of my weight on this blog.  (The blue dots are the actual weight, and the red dots from straight line fits to the data to figure out how fast I was losing weight.  Each dot is my average weight for that particular week – week zero was when I started.)  The shape of the curve is pretty interesting in itself, and I’ll come back to that point in a later post. Other details: I am 5’9” (178 cm) tall, which implies a Body Mass Index of about 23 at my current weight. This is well within the region considered healthy. I have a 32” waist (down from 40”), meaning a waist-height ratio between 0.4 and 0.5, again generally considered to be in the healthy region.  All of my vital stats (blood pressure, trigliceride levels, cholesterol levels, blood sugar, and heart rate) improved when I lost this weight, so I think I can safely say that I am in better health now than when I started.

Before I begin discussing weight loss methods, there are two points I want to make:

  • If you decide to lose weight, please talk to your doctor first and discuss different options, how fast you should lose weight, and what your goal weight should be. The methods I describe here should work for anyone in reasonable health to begin with, but are not good for everyone.
  • There are many fad diets and exercise plans out there. What I am describing are techniques for losing weight rather than a detailed specific plan. In particular, for reasons I will discuss in a later post, I am not going to specify particular foods one should or shouldn’t eat to lose weight.

These techniques are straightforward. This doesn’t mean they are easy! I don’t know why, but there are very few things worth doing in this world which are easy. They are also discussed in varying different forms in other places on the web and elsewhere. What I am discussing uses the same basic underlying ideas as other plans which range from very complicated (The Hacker’s Diet) to the very simple (such as a plan discussed by Tom Murphy). It is also similar to commercial plans such as WeightWatchers. Any and all of these work if you follow them, so don’t just read what I’m saying. In point of fact, the approach I took when I wanted to lose weight was to gather up as much information as possible from different sources and evaluate them. I considered WeightWatchers, but because I am a poor professor and a cheap bastard, I decided to formulate my own plan. (One later post will include instructions on how to effectively exercise at home without paying any money for equipment or a gym membership.)

So: here is the big plan for losing weight. It involves three parts, each equally important:

  1. Exercise more than you currently do;
  2. Eat less than you currently do;
  3. Weigh yourself every day and record the weight, but make plans based on weekly averages of your weight.

Here’s an easy way to remember this: sweat, starve and scribble. (Don’t really starve yourself, of course…) A few points regarding this:

  • Some people are going to read this and think,”well, duh — this is obvious!” Well, maybe, but there are a lot of fad diets or exercise routines out there which attempt to circumvent these rules. IMHO, they may work for the short term, but are probably unsustainable. What I am writing about is sustainable, and based on real science, at least as best I understand it.
  • The type of exercise doesn’t matter much as long as it is hard, aerobic exercise. I started out doing 45 minutes on an exercise bike, three times per week, which seemed like a reasonable way for me to begin. I’ve ramped up the duration, frequency and intensity since then, but again I will discuss this in a later post. I’ve also added other aerobic exercises which don’t require a machine (again, to be discussed in a later post.) Pushups, situps and other types of conditioning exercises won’t work for losing weight, although they’re good for other things.
  • The eating less part is more difficult, as it is pretty hard to count calories accurately. As a rule of thumb, try to go to bed slightly hungry (Not starving! Not with a belly crying out to be filled!) Slightly hungry seems to be a good measure for most people if you want to lose weight.
  • Keeping accurate records of your weight is as important as the other two aspects of the plan! Try to use the same scale each time at the same time of day (just after waking for me), and if possible, weigh yourself nude. (Clothing adds anywhere from about 1 to 5 pounds to your weight.) Some people use their computers or apps for their smartphones; I write my weight in a Monthly Planner book, but use an Excel spreadsheet program to calculate averages.
  • Plan for the long term. Don’t try to lose too much weight too quickly. My doctor and I decided that losing between half a pound to a pound per week was healthy, so that’s what I attempted (and largely succeeded at.) Again, discuss this with a doctor before beginning!

In the next several posts I am going to go into detail on how to do this. The next post will introduce the “master equation” for dieting, and discuss its implications.