Chapter 4

Toxic food environment Toxic physical activity environment

There’s more energy (calories) per capita than ever before.

Eating out is increasingly common.

Portion sizes are exploding.

Advertising budgets of healthy food and eating campaigns are dwarfed by the food industry.

Americans: Spent 19% of food dollars on restaurant food

in 1958 but 41% in 2009 Spend $222 Billion at restaurants and 118

billion on fast food a year. Consume 1/3 of our calories outside the

home On average, eat out 4 to 10x a week Spend $800 million a day on restaurant food Certain parts of the USA have seen a 60%

increase in new restaurants

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Time spent in front of a TV or computer screen is on the rise.

Non-motorized travel to work and school is declining. Jobs are more sedentary, leading to a less active

workforce.

Incidence has doubled since 1970’s

2/3 of American adults are now overweight or obese 1/3 are obese!

Rates are higher for African Americans and Hispanics

Genetics (accounts for 50%-90% of the variation in body fat)

Age Lifestyle Race or ethnicity Socioeconomic status Psychological factors

(e.g., emotional eating)

Weight is under substantial genetic control

Accounts for ~1/3 of BMI variations

Genetic influences contribute to differences among individuals in resting metabolic rate, body fat distribution and weight gain in response to overfeeding

Some people are predisposed to be obese which is readily nourished by a high fat, low activity lifestyle

More calories Bigger portions Fast food Physical inactivity Increased technology Passive entertainment Socioeconomics (obesity

and poverty high correlation)

Prenatal factors Childhood development Genetics Social networks Emotional influences

46% of Mexican females and 35% of males

48.6% of black African-American females and 30.9% of males

32.9% of white females 32.9% of males Diabetes more common among

minorities Ideal bodyweight different based on

culture

Hunger versus appetite Satiation versus satiety Energy balance

Energy output: basal metabolism, physical activity, thermic effect of food, thermogenesis

Energy intake: fat, carbohydrate, protein, alcohol

Energy imbalance (positive versus negative)

Eating more Less Energy Expenditure Or Both = Weight gain, specifically adipose

tissue

Lipids are stored in fat cells of adipose tissue.

The amount of fat that someone has involves the number of cells and the size of those cells

The number of cells increases fastest in growing children just before puberty.

The more obese the child, the faster the cells increase

Fat cells will also expand in size (hypertrophy). Fat droplets will fill the cell.

When they reach full size, they can also divide (hyperplasia)

Fat Cell Development

Obesity is directly related to amount and size of cells

With weight loss, cell size diminishes, but fat cell amounts do not decrease

Those with an average number of fat cells will be able to hold onto weight losses easier

Basal and resting metabolic rateBMR is the minimum amount of energy spent

during a fasting state to keep the body performing basic bodily functions.

RMR is similar to BMR but measures the activity to keep the basic body functions going in a nonfasting, noncompletely rested state (10% >BMR).

Thermoregulation Physical activity above resting levels Processing food/digestion

RMR, TEF and TEE TEF 10% of daily caloric

expenditure Exercise (TEE) is the most variable

in sedentary individuals 15%May be 35% in some active individualsRMR stays elevated after exercisethe higher the intensity of the exercise

the higher RMR after exerciseLow intensity does not have this effect

Closely related to Fat Free Mass (FFM)

24%-28% of weight-loss may come from FFM in diet only persons

11-13% of weight loss from FFM in exercising dieters

Energy In = Energy Out Weight Stays the same

Weight loss through dietary means alone often lowers RMR due to loss of muscle (FFM).

Weight loss from exercise can help to preserve and enhance FFM

Small changes, moderate losses, reasonable goals: .5 to 2 pounds per week or 1% body weight/week

Lean individuals who desire fat loss for appearance/performance will lose fat more gradually than the individual who has excess fat

Rapid weight loss in lean individuals can result in 3 times more lean tissue loss (FFM) than fat loss

Diet composition—amount of macronutrients (protein, fat, carbohydrate), fiber, energy density

Gastrointestinal sensations—stomach and intestinal distension

Hormonal and neurological factors—neuropeptide Y, serotonin, ghrelin, leptin

Cognitive, social, and environmental factors—eating with others, clean-plate club

Hidden factors—plate, bowl, or cup size

Height–weight tables Body mass index (BMI) Body composition

Skinfold measurements Dual-energy X-ray

absorptiometry (DXA) Hydrodensitometry

(underwater weighing) Bioelectrical impedance

analysis (BIA) Body-fat distribution

Waist circumference Waist-to-hip ratio

Body image

In the United States, fat is generally considered to be a negative attribute that is under a person’s control.

The ideal body is thin and lean or muscular.

Stigmatization of overweight and obese people is widespread and may be worsening over time.

Consequences include reduced self-esteem and negative body image.

Health at Any Size is an acceptance movement.

How Might Each JoggerBe Viewed by Society?

Health at Any Size (HAAS) is a size-acceptance movement that attempts to help large people be healthy.

A study of more than 25,000 men found that cardiorespiratory fitness was a better predictor of heart disease than body weight was.

A study of women also found that lack of physical activity was a better predictor of heart attack than weight was.

Set sensible goals. Develop a healthy

weight management lifestyle.Eat healthy by being

aware of nutrition value and calories of food.

Be physically active.Know how to modify

your eating behavior.Take advantage of self-

help opportunities.

Weight cycling (yo-yo dieting)

Popular dietsLow-carb, high-protein

dietsLow-fat dietsNovelty dietsVery-low-calorie diets

Healthy weight control programs not “diets”

Findings from National Weight Control Registry of people who have maintained a weight loss of at least 30 lb (13.5 kg):Consume slightly less

than 1,400 calories.Engage in high levels of

physical activity.Monitor weight.

Entering college Getting married During and after

pregnancy Holidays

Spot Reduction Saunas, sweat

suits and body wraps

Vibrating belts Electrical

stimulators Fad and starvation

Diets

Packaged foods, food combinations, supplements, exclusion of certain foods or food groups/macronutrietns

Any diet will lead to weight loss if energy intake is reduced

Potential increased loss of lean body mass

High risk for nutritional deficiencies

Long term efficacy, safety, maintenance is unknown

Community organizing and action

Schools and workplaces Media and advertising Food packaging and labeling Financial and economic

incentives Transportation and urban and

rural development