Effect of Exercise on Diet

This entry is part 2 of 11 in the series Training Programs

Beyond burning calories, exercise has three major impacts on your weight: appetite suppression, appetite change, and the little-recognized effects of regularity.

Originally published 2003

It is a truism that, to lose weight, you need to eat less. But how do you go about lessening your appetite, so you do eat less? One way is to eat high-quality food, which reduces your appetite because you are getting the nutrients your body needs. Another way is to utilize the effects of exercise. Sustained exercise is an extradorinarily effective appetite-suppresant that not only changes how much you eat, but what you eat. In addition, the body’s hormonal adjustments to regular daily exercise, regardless of intensity, holds an important key to progressive, fat-burning weight loss.


When I was working in Ohio, there was a state park with a nice collection of trails and mild hills situated mid-way between my home and the place where I worked. One spring, I became a habit to stop at the park after work and run for half an hour or so (20 min. minimum, 40 min maximum) on the way home.

It was a habit I kept up for nearly three months. During that time, my body underwent profound metabolic changes. This article relates those experiences.

A Progressive Cycle

First, let me say that I did nothing but easy running for the entire time — except for when I ran up a hill, which I loved to do whenever possible. Mostly, though, I just relaxed, “zoned out”, and meditated on the scenery as I skimmed along the ground as effortlessly as possible. (At least, that’s what it was like at it’s best.)

And since I loved to explore while running, I frequently found myself at a dead-end, where the trail seemed to peter out. I might stand around for a few minutes, hunting for a continuation of the trail before eventually finding one or deciding to return. So I often had short breaks during the run.

I started with short runs of 20 minutes or so. But after a few weeks, I found that I began wanting to run for longer periods of time. I chose Friday as the “long run” day. I’d chose a park somewhere in the city, drive to it, and run for upwards of an hour. It was a time to explore, a time to visit new scenery, and I loved it.

A month or two into the process, I began running seriously long distances on the weekends. I had started by running 30 to 40 minutes on weekends. After a month or two, I was running an hour or two on
one day and 20 or 30 minutes on the other.

One weekend, I was seriously demented, and wound up on the longest run I had ever undertaken — 22 miles. It took a little over 4 hours. By the end of it, I thought I was going to die.

More accurately, I no longer cared whether I lived or not. That point was brought home when a car came up to a stop sign as I was in the cross walk. It came up fast enough that you wonder if it’s going to stop. But by that time, I was beyond caring. I just wanted to get home. I figured, what the hell, if it doesn’t stop it will put me out of my misery. I was already crawling along at a snail’s pace, but I crossed in front of that car without the slightest pause.

(The next day, though, my legs felt fine! The real problem was the sunburn. That didn’t go away for a week!)

A few weeks after that, I quit running. I was just bored with the whole thing — or so I thought. At the time, I didn’t realize that boredom and an attitude of “what’s the use” are a major sign of overtraining. Had I know it then, and dealt with it, I might have been able to keep running. But I didn’t so I quit.

Much as I would like to resume that running cycle with greater wisdom, unrelated injuries that led to knee surgeries have made it impossible. I still have running dreams, though. In them, I discover that I “forgot” that my knees are totally healed, and I glide a long the ground without even feeling it, totally weightless and relishing the “flying” sensation.

Metabolic Changes

The whole episode lasted about 3 months. I was extremely happy, what with the running endorphins coursing through my system regularly. But it was the metabolic changes that were of major interest.

Of course, my body-fat percentage dropped and my legs grew stronger, as evidenced by the fact that I was able to run for longer and longer periods of time. But there were two other changes of particular note:

  • Regularity
  • Appetite change


The first change was how “regular” my metabolism became. Because I ran at the same time every day, the rest of my metabolism began to arrange itself around that anchor.

I began to get tired at the same time each night, and go to sleep at the same hour. I began to rise at the same time, get hungry and eat at the same time, and go to the bathroom at the same time.

I suspect that the regularity I experienced contributed a great deal to the fat loss I experienced during that time.

I believe that to be the case, primarily because the body is an *incredibly* intelligent adaptive mechanism. It is in, fact, the most powerful adaptive mechanism that has ever been present on this planet.

That the body has “a mind of its own” is clear to anyone who has tried to diet their way to weight loss. Instead of controlling the body through will power, the body turns out to have an amazing variety of
tricks that subvert the process:

  • The body begins to store energy-containing food to maintain basic bodily operations, instead of burning it for energy immediately. To the body, this is a matter survival. So your energy level drops, and your activity level drops, as well.
  • Muscle consumes energy. Fat doesn’t. So your body consumes as much muscle as it can for energy, saving the fat for later. That way, it minimizes energy demands, while storing as much energy as possible.
  • At the same time, it re-configures it’s enzyme balance to save as much fat as possible. So when you eventually lose the “battle of wills” and go back to eating, you put on fat in a hurry. (And with less muscle to burn it, which helps it come back rapidly.)

When you understand that the adaptive mechanism that is your body is really *that* smart, it makes sense that regularity promotes fat loss. In a matter of weeks, the body comes to “know” that more energy will be provided at a given time.

If you’re exercising regularly, the body is also smart enough to “realize”, in it’s less than conscious way, that muscle is good (makes the activity easier) while fat is bad (makes the exercise harder). So it just
naturally starts to burn fat, and spare muscle.

The bottom line here is that it may well be the *regularity* of exercise that is the most significant factor in losing weight, rather than the quantity or quality of it. That’s an important thing to know, given the
ubiquity of labor-saving devices in industrial civilization — with mechanical advantages like elevators, cars, and shopping carts, about the only exercise we get anymore is putting away the groceries!

Appetite Change

The other major change that occurred during this time was a sudden, dramatic change in my appetite. Unlike the effect of regularity, which appeared in a week or two, the change in appetite took something over a month.

I was somewhere in the neighborhood of 4 to 6 weeks into the process when I experienced something I will never forget.

I walked into a steak house, filled with the wonderful aromas of steak and baking potatoes, and I didn’t even notice them. Instead, my eyes zeroed in on the salad bar, and I began to salivate. I could not *wait* to sink my teeth into a big, juicy salad, filled with lettuce and tomatoes and cucumbers.

That was new for me. Normally, I hungered for those juicy steaks barbecuing on the grill, and didn’t even notice the salad. But now, all I saw was the salad. Heck, I didn’t even want dressing. I just wanted to feel those gorgeous hunks of leafy greens crammed into my mouth, chewed to a liquid paste, and gliding velvet-like down my throat.

I mean to tell you, I was turned *on* by the thought of salad.

When I ate the salad, it was everything I had imagined. It was lush, beautiful, delicious. The steak and the potato? Didn’t know. Didn’t care. Didn’t want it. I just positively *lusted* after that salad.

I started making salads at home for dinner. I began making up salad songs. I still sing them, to this day, when all is right, I’m feeling good, and I’m making a big salad:

  • Oh, salad. Oh salad salad. Oh, oh, salad, oh.
  • Sal-ad on the range, where the deer and sa-al-ad play…
  • If I had a sal-ad, I’d salad in the morning, I’d salad in the evening…
  • On top of my sal-ad, it’s covered with cheese, …
  • I left(ate) my sal-ad, in San Fran-cis-co.

I have to admit, this is nuts. But there is *no* song that cannot become a “salad song”. But you’ve got to be pretty gonzo about salad to begin thinking like this.

The thing is, we all *know* that fruits and vegetables are the healthiest thing we can possibly eat. With their high fiber content, high vitamin and mineral content, and nutritional enzymes, they can keep us healthy at the same time they are promoting weight loss.

But knowing that doesn’t make us *want* them any more. We may even have to force ourselves to eat fruits and vegetables, instead of hungering after them ravenously. But when we experience the latter,
weight loss is sure to follow.

Other Kinds Of Exercise Potentially More Effective

In the interests of accuracy, it is no doubt worth mentioning that the kind of exercise I was doing (easy running) is not even the most effective kind of exercise for weight loss.

The *most* effective exercises for fat loss are characterized by constant low-level activity interrupted by spurts of high-intensity activity (which tend to produce muscle at the same time).

Exercises like competitive badminton, basketball, soccer, and competitive volleyball, for example, keep you in more-or-less constant motion, while occasionally demanding bursts of energy in the form of jumps or sprints. These
activities have been shown to be the most effective fat burners.

One example was a fat kid who used to live across the street. All through high school and into junior college, he was just really fat. A really nice, jovial kid. But fat. Then he took up badminton.

A year later, I didn’t recognize the kid. He had slimmed down something fierce, and he had taken up gymnastics. Two years later, his own mother wouldn’t have recognized him. Fit? He could have been on the cover of Sports Illustrated.

The major point here is that pretty much any activity you choose, if done *regularly*, will tend to have a big impact on your diet, and your weight. It can be very strenuous like soccer, somewhat strenuous like easy running, or even mildly strenuous, like walking or gardening. Although vigorous activity can produce faster results, only *consistent* activity will produce any results whatever.

In fact, walking has been shown to be a great exercise for weight loss. The reason, I suspect, is to do the relative ease with which you can achieve *regularity* in your exercise regimen.


Consistent exercise, due to the combined effects of regularity and appetite change, is perhaps the major key to effective weight loss. Other important factors are quality of the diet, and strength training for
muscle growth and a balanced physique. But consistent, low-level exercise is most likely to be effective, because it tends to lead naturally to improved diet, to higher energy levels, and therefore to
greater interest in exercise and strength development.

Final Note:
As of this writing, I am taking up horseback riding. The idea is that the continuously bent-legs with which you ride will minimize stress on the knees, and I’ll be able to return to to the regular outdoors activity which has been for so long been denied!

Copyright © 2003-2017, TreeLight PenWorks

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