Energy Balance and Weight Control

Components of Body Weight Factors that Influence them

Water

Lean body mass

Skeletal mass

Fat mass

Gender/LBM/exercise/diet

Gender/genetics/exercise/diet

Gender/genetics/exercise/diet

Gender/genetics/exercise/diet

Gender and genetics typically explains about 40 – 60% of adult body weight. Exercise and diet explain about 40 – 60% in relatively equal contributions.

Body fat is an indicator of energy balance: Calories IN vs. Calories OUT If energy IN excess energy OUT then body fat

INCREASES as the excess calories are converted to fat for storage.

A pound of fat = 3,500 calories◦ Beyond daily expenditure

If you drank just one extra Coke each day (150 calories) beyond your daily calorie need, how long would it take you to gain 5 pounds of fat?◦ 116 days

To lose a pound of fat, you need to EXPEND 3,500 more calories than you take in.

Energy In (eating)What factors influence eating behavior? Why do you eat what

you eat when you eat it?

Internal Factors External Factors

Nutrient levels

◦ Glucose (short term)

◦ Fat (long term)

Hormones

◦ Gut hormones (CCK)

◦ Insulin

Neurotransmitters

◦ Serotonin

Tastes good/looks good

Boredom

Social interaction

Emotional needs

Eating as a sport

It’s time to eat

Energy Out: On what do we expend energy?

Basal metabolic processes (60 – 70%)◦ Respiration

◦ Circulation

◦ Nerve transmission

◦ Tissue replacement, turnover, repair Epithelial cells, bone, LBM, etc

Basal metabolic rate = BMR = quantification of calories expended on these processes

Energy Out: On what do we expend energy?

What factors influence the amount of energy expended via BMR?

◦ Body weight

If BW decreases, BMR decreases

◦ Lean Body Mass

If LBM decreases, BMR decreases

◦ Caloric restriction

If calories decrease, BMR decreases

◦ Genetics

Energy Out: On what do we expend energy?

Physical activity (20 –30%)

What factors influence the amount of energy expended on physical activity?◦ Body weight Increased body weight

burns more calories

◦ Intensity, type, and duration

Digestion and absorption (6 – 10%)

Obesity

Associated with an increased risk for almost every major chronic disease◦ CVD

◦ Diabetes

◦ Hypertension

◦ Cancer

Associated with infertility, pregnancy and surgery complications, arthritis, gout, gallbladder disease, and sleep problems

How is Obesity Defined?

The current method for assessing overweight and obesity is a relationship between weight and height called the Body Mass Index or BMI

BMI = Weight (kg) ÷ Height (m) 2

BMI = Weight (lbs) ÷ Height (in) 2 x 702

Underweight = < 18.5

Normal = 18.5 – 24.9

Overweight = 25.0 – 29.9

Obesity = > 30.0

Limitations of BMI Does not consider body composition

Does not consider location of excess weight◦ Waist vs. hips and thighs

◦ Waist circumference recommendations for: Men: < 102 cm (40 inches) Women: < 88 cm (35 inches)

Cut-offs for overweight and obesity assume on-size-fits all with respect to age and ethnicity

The BMI and weight for height tables serve as a tool for defining obesity. But how much weight should a person lose?

Weight Control from a Biological Point of ViewWhy is it difficult to lose weight and keep it off?

Genetic differences

Gender differences

Food is life

Response to food restriction

Adaptation to starvation

Environmental influences

Changes in body weight and composition as a result of weight loss

We don’t like to exercise

Keys to Successful Weight Loss and Maintenance of Lost Weight Set reasonable goals for weight loss Eat a balanced diet of REAL foods that is

reasonably low in fat and high in fruits, vegetables, legumes, and whole grain carbohydrates

Limit consumption of empty liquid calories Pay attention to calorie intake Avoid feelings of denial Be honest and pay attention to your eating

behavior Make regular, moderate exercise a part of your

routine

What do we know about successful losers? The National Weight Control Registry has

been collecting data on a large group of men and women who have lost an average of 65 pounds and kept off a minimum of 30 pounds for at least 5 years◦ Calorie restriction and exercise◦ Over 50% engaged in moderate to heavy

exercise◦ Fat intake averaged 24% of total calories◦ 50% continued to count calories or fat grams◦ About 50% lost weight without formal

assistance

Fad Diets Promise:

Rapid weight loss◦ Example

No calorie counting◦ BUT most fad diets

do count calories by telling you what to eat and when to eat it

To evaluate a diet plan, ask:

How long has anyone been able to stay on the plan?

How long could you stay on it?

Is it nutritionally balanced?

Does it encourage exercise?

Fad Diets by Stephen Pfleger

FDA-Approved Diet Pills

Sibutramine (Meridia)

◦ Increases serotonin

◦ Can raise blood pressure

◦ Has only been approved for use in the truly obese (BMI > 30)

◦ Use results in loss of 10-15% of starting body weight

◦ Discontinuation results in weight gain

FDA-Approved Diet Pills

Xenical (Orlistat)

◦ Works by blocking fat absorption

◦ Side effects: oily stools, flatulence –unabsorbed fat in the large intestine

◦ A clinical trial found that volunteers lost 10% of body weight vs. 6% for those on a placebo

Alli

◦ Over-the-counter, less potent version of xenical

Other Products

Many dietary supplements (vs. drugs) claim to aid in weight loss◦ Some act as diuretics (e.g., high doses of

vitamin C) or laxatives (e.g., senna, casara) that promote water loss

◦ Stimulants (e.g., ephedra/Ma Huang, bitter orange, guarana/caffeine) can increase BMR slightly but are linked to many adverse health effects (e.g., strokes)

◦ The vast majority are ineffective (e.g., chromium piccolinate, Chitosan)

◦ None will produce significant, sustainable weight loss