Nutrition in Crisis: Flawed Studies, Misleading Advice, and the Real Science of Human Metabolism by Richard David Feinman

Author:Richard David Feinman [Feinman, Richard David]
Language: eng
Format: epub, mobi
Tags: Health & Fitness, Diet & Nutrition, Diets, Nutrition, Diseases, Cancer, Diabetes, Medical, Endocrinology & Metabolism, History
ISBN: 9781603588195
Google: 9oxjvAEACAAJ
Barnesnoble:
Publisher: Chelsea Green Publishing
Published: 2019-03-26T07:00:00+00:00

Beyond “A Calorie Is a Calorie” 133

4. Several mechanisms, particularly substrate cycling and gluconeogenesis,

are involved. Experimentally, inefficiencies in digestion and metabolic

processing (the so-called thermic effect of feeding) contribute as well.

Many people find metabolic advantage counterintuitive because the

idea of energy conservation has been so deeply ingrained in their minds.

I will explain the fallacy. I will present some of the data and then explain

how the process plays out in terms of biochemical mechanisms.

The Data

There are basically two kinds of diet experiments. Some clearly show

energy balance and some clearly do not. Here’s an example of the former:

If you take a normal person, keep them in a hospital room, and feed them

constant calories (figure 9.1), you will find that it doesn’t matter much how the calories are distributed among different foods. “Wide variations in the

ratio of carbohydrate to fat do not alter total 24-h energy need”2—their

weight will stay roughly constant. In some experimental cases, like this, a

calorie is indeed just a calorie. Two people who are roughly similar in age

and health will respond similarly to two isocaloric (same caloric value)

diets regardless of the diet composition (amount of fat, carbohydrate, and

protein). This means that, yes, calories count. Yet there are many exceptions.

The energy balance shown in figure 9.1 is achieved by biologic mecha-

nisms, not the laws of thermodynamics. In those cases, where everything

balances out, it isn’t physical laws but rather the unique characteristics of FPO

Days

10

24

38

52

66

80

94 55 W

54 eigh

53 t (kg)

52

51

10% Fat

70% Fat

Figure 9.1. A thirteen-week study of a subject first on 10 percent (75 percent carbohydrate) of energy intake as fat and then on 70 percent (15 percent carbohydrate) of energy intake as fat. From J. Hirsch et al., “Diet Composition and Energy Balance in Humans,” American Journal of Clinical Nutrition 67, no. 3 (1998): 551S–555S.

Chelsea Green eGalley. Not for copying or distribution. Quotation with permission only. UNCORRECTED PROOF.

134

Nutrition in Crisis

FPO

A

B

Wk 0

Wk 12

Wk 0

Wk 12

0

0

0

VLCKD

-2

Low Fat

-5

-5

-4

oss (kg)

-10

-10

-6

t L

oss (kg)t L

eighW -8

eigh -15

-15

W

-10

-20

-20

-12

VLCKD

LFD

0

1

2

3 4

5

6

7

8 9 10 11 12

-25

-25

Week

A

B

Wk 0

Wk 12

Wk 0

Wk 12

0

0

0

VLCKD

-2

Low Fat

-5

-5

-4

oss (kg)

-10

-10

-6

t L

oss (kg)t L

eighW -8

eigh -15

-15

W

-10

-20

-20

-12

VLCKD

LFD

0

1

2

3 4

5

6

7

8 9 10 11 12

-25

-25

Week

Figure 9.2. Comparison of low-carbohydrate ketogenic diet and low-fat diet. From J. S. Volek et al., “Carbohydrate Restriction Has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet,” Lipids 44, no. 4 (2009): 297–309.

Chelsea Green eGalley. Not for copying or distribution. Quotation with permission only. UNCORRECTED PROOF.

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