Fundamentals
of Nutrition

What is a
Food Portion?

Your Nutrition Style

Your Activity Style

Physiology
of Nutrition
Lecture Series
Lecture 1
Lecture 2
Lecture 3
Lecture 4
Lecture 5
Lecture 6
Lecture 7
Lecture 8

Lecture 1

Introduction to Nutrition in Western Civilization:
Modern Man's Failure to Adapt to Changing Diets and Lifestyles

Taken in perspective, modern man is underactive and overnourished relative to the human genetics which evolved in a time of food scarcity. The adaptation to starvation so critical to man's survival is now maladaptive, leading to the prominence of obesity as the most prevalent nutritional disorder in the U.S. Even for individuals who are not obese, there is a progressive decrease in muscle mass and increase in fat mass with age. Why is man so prone to deposit fat? Why has man not adapted genetically to his changed modern circumstances? By the end of this lecture you should be able to answer these two questions.

The History of Man

" Hunter-Gatherers " : Australian Aborigines, Some Native Americans

" Agricultural Peoples" : Pima Indians, Asian Indians, Pacific Islanders Japanese, Chinese

Evolution of the Human Diet and Lifestyle

"Hunter-Gatherer" : Scarcity of Foods: Subsistence Level
Wide variety of wild animals, and uncultivated plant foods.

"Agricultural" : Relative Abundance, Cycles of Feast and Famine
Cultivated Crops (mainly cereals) and Domesticated Animals (meat, milk)

Modern Western Diet: Abundance of foods, increasing world population
Wide variety of sources, High proportion processed
High in Simple Sugars, High in Fat

"Thrifty Genotype: The Hunter-Gatherer's Friend"
[J.V. Neel Am. J.Hum. Gen. 14:353-62,1962]
An ability to efficiently deposit fat in times of food abundance via a high insulin response or quick "insulin trigger". Selective insulin resistance to glucose disposal and gluconeogenesis with preserved insulin action in inhibiting lipolysis and promoting lipogenesis. [Updated 1982]

Animal Foods

• Mammals, birds, reptiles, insects, marine species
• Everything edible on the animal carcass was eaten
• Non-domesticated animals lack fat deposits in muscles (does not "marble") and under the skin.
• Even liver and brain while rich in cholesterol and fat were also rich in long chain n-6 and n-3 fatty acids.

Plant Foods

• Uncultivated Plants and Honey (Highly Valued)
• Rich in fiber, low in sodium, rich in calcium,
• magnesium, and potassium.
• Low Energy Density, Low Glycemic Index

The Hunter-Gatherer's Lifestyle

Goal: To maximize energy intake and minimize energy output

Reality: Low energy intake (subsistence) and high output

Physical Activity: 3-5 hr. per day spent in sustained activity
Digging, walking briskly, chopping with stone axe
Moderate to high level of physical activity unavoidable

Minimization of unnecessary physical activity

Food Preferences

• Depot fat
• Organ meats
• Fatty insects
• Honey

Eating Patterns: Food consumed immediately by gorging and wastage rare
Would gorge 2 to 3 kg of animal after successful hunt
Would also gorge on honey ,eggs, insects or fat

Israeli Sand Rat (Psammomus obesus)
Spiny Mouse (Acomys caharinis)

Sedentary Lifestyle of Laboratory Cage and Rat Chow Leads to:

• Minority of Animals with Normal Glucose Metabolism
• Majority with wide variation of abnormalities including
  • Impaired Glucose Tolerance
  • Hyperinsulinemia
  • Insulin Resistance
  • Frank Diabetes and Hypoinsulinemia

1. There was an adaptive advantage to hanging on to fat and calories in ancient times, since there was not enough food to eat.
2. The sudden appearance of agriculture, food technology and food production overwhelmed our body’s ability to adapt to overnutrition.
3. As a result there is now an epidemic of obesity in the U.S. while many countries around the world continue to have endemic starvation.
4. The rapid export of American foods and lifestyles have created an international epidemic of obesity in some developing countries at the same time .
5. Immigrants to the U.S. develop the habits, lifestyles, diets and suffer from the chronic diseases characteristic of Americans within a generation of coming here if they give up their traditional food habits.

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