In 1977 Covert Bailey wrote a best-selling book, Fit or Fat, pointing out that the
“overweight” problem people have is really a problem of too little muscle mass and
too much fat or adiposity. We are “overfat” when too high a proportion of our
total body weight is made up of fat. Weight is gained when the calories expended
by the body, including those used during physical activity, are less than the calories
you take in through food and drink. Research shows that physical activity can help
attain and maintain a normal weight. However, exercise is an inefficient way to lose weight compared
to the restriction of calories.
As fitness improves, muscles become more sensitive to the effects of insulin, and
lower levels of insulin are needed to keep blood sugar in a normal range and help
avoid the overshoot of insulin that leads to low blood sugar, excessive hunger, and
overconsumption of food. Increased physical activity, especially when resistance
and aerobic exercise are combined, reduces diabetics’ need for insulin, and may
prevent the progression of pre-diabetes.
When losing weight, as much as one-third of the weight loss can come from the
muscle that it is desirable to keep, rather than from the fat we want to lose. Exercise
when dieting is one strategy to counter and minimize this. In one study, dieting
walkers and weight trainers both lost about 20 pounds, but the weight-trainers
lost only two pounds of muscle compared to the walkers—they lost four pounds.
Both groups lost more fat than dieters who did not exercise.
Another dietary strategy to retain and build muscle mass during both dieting and
weight-training is to consume a plentiful supply of protein. An analysis of 17 clinical
trials of people over age 60 (average age 73) found that consuming 10 to 35 grams
of extra protein per day significantly increased lean muscle mass and leg strength in
men but not much in women.
A review of 49 studies found that weight-trainers
consuming 1.6 grams of protein a day per kilogram of body weight had modestly
larger increases in muscle size and strength than those consuming lesser amounts.136
Higher amounts than 1.6 gm/kg of protein were not beneficial. Benefits did not
differ according to the protein’s form (liquid or solid), or the source (plant or animal),
or the time of day it was ingested. For a 70-kilogram (154 pound) man, 1.6
gm/kg of protein would be 112 grams a day of protein, precisely double the USDA
nutrition goal recommended 56 grams a day for men. The USDA recommendation
for women is 46 grams a day. This is not a difficult goal to reach from plant and
animal sources. A cup of beans contains 15-18 grams of protein, a chicken breast 43
grams, yogurt 10 to 20 grams per cup, and an 8-ounce glass of fat-free milk contains
approximately 8.5 grams of protein—nearly 40% of the total calories of skim milk.
For most people, an important long-term solution to the problem of being “overfat”
is to both decrease the calories consumed and increase the calories expended by
becoming more physically active. Increasing physical activity builds muscle and,
assuming no increase in calories ingested, “burns” fat calories. The Guidelines
suggest that the equivalent of 150 minutes of moderate-intensity activity a week
should be considered a minimum to help to maintain a normal weight. Some people
will need much more exercise to maintain a low level of body fat. For most people,
getting to and staying at a healthy weight requires both regular physical activity and
healthy nutrition without excess calories.
The National Runners and Walkers Health study has found that study participants
who were runners had lower body mass indices and lower waist circumferences than
the walkers, even though energy expenditures did not differ very much. Age-related
weight gain was attenuated by running in both sexes and by walking in women.
One possibility relating to the difference between walkers and runners is that the
more intense exercise of running helps to control appetite. One study on a small
number of subjects indicated that compared to walkers, runners have higher levels
of the appetite-suppressing hormone peptide YY and are less interested in food after
running than walkers are after walking.
There is some evidence that you can more efficiently burn fat if you exercise on an
empty stomach rather than after a meal. In one study, twice as much body fat was
mobilized from muscle and other body sites after exercise on an empty stomach
than after a high-calorie shake. Rather than deriving energy from the recent meal,
the body’s stores of glucose, glycogen, and fat were mobilized.
To achieve or maintain a healthy weight, the Guidelines suggest meeting the minimum
level of physical activity. And if this does not suffice, either gradually increase
the level of physical activity (toward the equivalent of 300 minutes a week
of moderate-intensity aerobic activity), or reduce caloric intake, or both, until your
weight-control goals are met. By regularly checking body weight, you can find the
amount of physical activity that works for you.
For weight control, vigorous-intensity activity is far more time-efficient than moderate-
intensity activity. For example, an adult who weighs 165 pounds (75 kg) will
expend an additional 280 calories over baseline from a brisk 5-mile walk of 75
minutes duration at four miles an hour (these calories are in addition to the calories
normally used by a body at rest). That person can expend the same number of
additional calories in one-third the time (25 minutes) by running 2.5 miles at a 10
The Harvard Medical School provides a table that lists the calories burned in 30
minutes for people of three different weights according to activity, including walking,
sports, and everyday household activities. It is available at: https://www.
This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel.