Why fattening foods don't really exist...
You might have heard of so-called "fattening foods" —
foods that are more likely to cause weight gain than others. Unfortunately,
this common myth about fattening foods is one reason why many people
don’t lose weight as quickly as they’d like to.
Just the other day, for example, I was offered some reduced-fat
chocolate biscuits. Because they were low in fat, I was told they
were "less fattening" than normal biscuits. And because
they were supposedly less fattening, I was told I could eat more
of them!
Let’s compare cheddar cheese with a typical "diet"
food such as Melba toast. If I were to ask you which food was more
fattening, you’d probably say cheese, right?
Each gram of cheese contains around four calories. However, Melba
toast also contains four calories per gram. In other words,
the low-fat high-carbohydrate food (the Melba toast) contains just
as many calories as the "fattening food" (the cheese)
considered by many dieters to be off-limits.
When it comes to losing weight, the secret to success is to consume
fewer calories than you burn. It doesn't matter how many
diet supplements you use or how much exercise you do. If you're
eating the same number of calories as you're burning, your weight
will stay the same.
Another common myth is that stripping fat from your diet and replacing
it with carbohydrate increases your metabolic rate. In theory, filling
your plate with pasta but holding back on the high-fat sauce forces
your body to burn more calories. There is a small element of truth
to this, as it does take a few more calories to turn carbohydrate
into fat than it does to store the fat that comes from the food
you eat. However, the number of calories burned is so small that
it makes virtually no difference to your metabolism.
Some evidence for this comes from a six-week study at the Mayo
Clinic [3]. Overweight women were fed a diet with moderate amounts
of carbohydrate and a substantial amount of fat. Two weeks later,
they switched to a diet containing the same number of calories but
lower in fat and higher in carbohydrate. Yet the research team could
detect no change in metabolic rate. More importantly, the women
lost no weight and no body fat.
In fact, research at Vanderbilt University shows that after four
months on an extremely low-fat diet, dieters had a lower metabolic
rate than they did at the start of the study [4]!
Calories
A group from New Zealand’s Otago University report similar
results [1]. They managed to persuade a group of 32 endurance-trained
cyclists to alter their diets for 12 weeks. Half of the group consumed
a high-fat diet (47% of total calories came from fat). The rest
consumed a high-carbohydrate, low-fat diet (69% of total calories
came from carbohydrate).
Although the composition of the diets was very different, the total
amount of calories was almost identical. In other words, the energy
provided by both the high-carbohydrate and high-fat diet was the
same.
For the duration of the study, the cyclists maintained their normal
training program, consisting of between 6 and 25 hours of cycling
each week. The researchers found that body fat levels did not change
over the three-month period, simply because the calorie intake
of the cyclists was matched by their calorie expenditure.
It's also worth noting that some populations who habitually consume
a diet high in fat aren't always overweight. For instance, the Fulani
of the Jos Plateau (a tribe based in a mountainous state in northern
Nigeria) consume a diet that is roughly 48% fat [5].
Much of this comes from saturated fat such as palm oil and butter
oil. Despite a diet so high in fat, the Fulani are extremely lean.
However, if you look at the total amount of calories the Fulani
consume in a day, it's roughly 13 calories per pound of body weight,
which is very low compared to the standard American diet. The fact
that the Fulani are also more physically active than most Americans
also contributes to their low levels of body fat.
Body fat is nothing more than stored energy. If the amount of
calories you burn is equal to the amount of calories you take in,
then your weight will remain the same.
Related Articles
References
1. Brown, R.C., Cox, C.M., & Goulding, A. (2000). High-carbohydrate
versus high-fat diets: effect on body composition in trained cyclists.
Medicine
and Science in Sports and Exercise, 32, 690-694
2. Hudgins, L.C., Hellerstein, M., Seidman, C., Neese, R., Diakun,
J., & Hirsch, J. (1996). Human fatty acid synthesis is stimulated
by a eucaloric low fat, high carbohydrate diet. Journal
of Clinical Investigation, 97, 2081-2091
3. Roust, L.R., Hammel, K.D., & Jensen, M.D. (1994). Effects
of isoenergetic, low-fat diets on energy metabolism in lean and
obese women. American
Journal of Clinical Nutrition, 60, 470-475
4. Schlundt, D.G., Hill, J.O., Pope-Cordle, J., Arnold, D., Virts,
K.L., & Katahn, M. (1993). Randomized evaluation of a low fat
ad libitum carbohydrate diet for weight reduction. International
Journal of Obesity and Related Metabolic Disorders, 17,
623-629
5. Glew, R.H., Williams, M., Conn, C.A., Cadena, S.M., Crossey,
M., Okolo, S.N., & VanderJagt, D.J. (2001). Cardiovascular disease
risk factors and diet of Fulani pastoralists of northern Nigeria.
American
Journal of Clinical Nutrition, 74, 730-736
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