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Obesity

According to the National Center for Health Statistics, more than 64% of the US adult population is overweight (Body Mass Index >25 and <30 kg/m²); and roughly 31% of American adults meet the criterion for obesity (BMI > 30 kg/m²) - that is, about 59 million American adults.  Adult obesity has increased from 12.8% in 1976-1980 to 22.5% in 1988-1994 and 30% in 1999-2000. 

There has also been a striking increase in the prevalence of childhood obesity.  This leads to health problems for children and also increases their risk for various diseases as adults.  Physiologists, for many years, have remained at the forefront of obesity research and have uncovered much about its pathology. 

The following is a compilation of recent physiological research that explores obesity at its pivotal stages from womb to tomb. 

Prenatal

This very first stage of existence can mark the beginning of a lifetime of weight related problems.  Recent research shows that there are multliple factors that influence predisposition to obesity, including:

Exposure to certain hormones in the womb

• Neuropeptide Y- the hormone controls gluttony (Press Release: “Can female adult obesity be stopped at birth?” 

• Cytokine (Abstract: “Prenatal cytokine exposure results in obesity and gender-specific programming”

  • In rat studies, all exposed subjects had offspring that developed increased body weight

Mother’s health and habits

• Maternal diet – Mothers who ate a diet high in protein and low in saturated fats improved triglyceride levels and lipid profile of their offspring. (Press release: “High protein, low-carb diet during pregnancy improved triglycerides, fat metabolism in offspring”)

• Maternal malnourishment - Offspring of undernourished mothers were significantly inactive, obese and hypertensive when compared with normal offspring, even into adulthood. (Press Release: “Couch potatoes may be created in the womb, not at the dinner table”; Abstract: Fetal origins of hyperphagia, obesity, and hypertension and postnatal amplification by hypercaloric nutrition 

• Maternal alcohol exposure – Exposure to alcohol during pregnancy and/or lactation causes insulin resistance, a condition that increases likelihood of developing diabetes and heart disease (Abstract:  “Whole body insulin resistance in rat offspring of mothers consuming alcohol during pregnancy or lactation: comparing prenatal and postnatal exposure”)

• Post-natal environment

Childhood

A growing area of concern has been the rapidly increasing rates of obesity in children.  Statistics show that the number of obese children has tripled in the last 20 years.  Additionally, there has been a rise in the occurrence of type-2 diabetes, a disease with direct links to obesity, in children under 10.  Childhood is also a time when a predisposition to obesity begins to express, especially in children who overeat and/or lead a sedentary lifestyle. 

These trends are of particular concern because obese children often become obese adults.  Childhood obesity is recognized as a predictor of adolescent and adult obesity (Abstract:  “Childhood obesity: its incidence, consequences and prevention” ).  Overweight children, aged 10 to 14, with at least one overweight or obese parent were reported to have a 79% chance of overweight persisting into adulthood (American Obesity Association website: http://www.obesity.org/subs/fastfacts/obesity_youth.shtml)

Children with a body mass index (BMI) in the 95 percentile are likely to have obesity persist into adulthood. Evidence also suggests that obesity at this age has severe psychological repercussions as well.  Childhood obesity now accounts for $17 billion in health care costs each year.

Scientists have isolated a number of factors that have been associated with the development of childhood obesity, including:

Sedentary Lifestyle

• Inactivity directly relates to obesity at any age.  It goes against our ancient “hunter gatherer” body cycle. (Abstract:  “Waging war on physical inactivity: using modern molecular ammunition against an ancient enemy”) 

• Children develop habits when they are 5 to 10 years old that remain with them the rest of their lives, including that of a sedentary lifestyle.

• Getting adequate physical activity may be the most important factor in maintaining body weight and weight balance

• Some states curriculums no longer require physical education programs – removing some children’s primary source of exercise

Independent Food Choices

• In a rat study, it was shown that if there is a choice between healthy and fatty foods, subjects often choose the fatty option.  (Press Release: “Obesity by Choice”) 

• When children begin to make their own food choices away from their parents, they are more likely to pick unhealthy snacks

• School vending machines routinely stock junk food

• Much of the food marketed to children is unhealthy or not nutritionally sound

• Lack of education regarding portion control and overeating

• Food available in cafeterias for the most part has high fat and caloric content

Socioeconomics

• Research indicates that those in lower socioeconomic brackets continue to be more susceptible to obesity and inactive lifestyles throughout childhood

  • (Press Release: “High Risk Children From a Lower Socioeconomic School Provide Evidence That a Hormone Derived From Fat Cells May Indicate Who Is Susceptible to Type 2 Diabetes”)

  • (Press Release: “Combined Findings of a New Study Indicated Need for Improved Nutritional Practices for African American Females with Low Incomes”)

  • (Press Release:  New Study Of Obesity, Genes And Socio-Economic Status Uses Individual Growth Curves Of Body Fat Measures In Youth)

Adulthood

The Centers for Disease Control (CDC) now estimates that more than 60% of American adults are overweight, one in three of those being obese.  In 2001, it was estimated that more than 300,000 deaths per year were associated with overweight and obesity.  In adulthood, obesity becomes a health liability.  The leading killers of Americans (heart disease, cancer) often have a strong correlation with obesity.

Causes of adult obesity

• Unhealthy eating habits established in childhood, adolescence and late teens carry over to adulthood

• Sedentary lifestyle coupled with decreased metabolic rate

• Lifestyle changes due to technology such as elevators, cars, dishwashers, televisions, power lawn mowers, etc.

• Decreased metabolic needs and energy expenditure coupled with the same or increased food intake (Abstract: “Total daily expenditure in free-living older African-Americans and Caucasians”)

Related Diseases

• Complications/risk factors associated with obesity include: type II diabetes, hypertension, heart diseases, liver disease, some cancers, stroke, sleep apnea, osteoarthritis, gallbladder disease, depression and others.

• (Press Release: “’Obesity sleuths’ find chronic diseases are linked to a breakdown response to what our human DNA is expecting”)

• (Article: “Rising rates of adult disability, likely caused by obesity”)

Elderly

Aging research represents a growing area of both physiological and general scientific study.  Understanding causes and function of obesity as one ages has become a main focus.

• Aging is associated with a reduction in metabolic rate (the amount of heat produced in the body).  This change may promote increased fat storage and obesity in the elderly (“Effect of aging on -adrenergically mediated thermogenesis in men”)

• The amount of fat in the body and its distribution predicted their response to insulin and other metabolic disorders in women (”Contributions of total and regional fat mass to risk for cardiovascular disease in older women”)

• Press Release:  “Physical Activity In The Elderly Ruled In Part By Genetics”)

• Article:  “Obesity Hits Elderly Harder Than Younger Patients”

• Reduced function, decreased physical activity and decreased energy expenditure lead to fat accumulation and fat redistribution in elderly (“Obesity in the elderly: who should we be treating, and why, and how?”)

What Can Individuals Do About Obesity At Any Age

The news about obesity can be overwhelming, but there are things that individuals can do to protect their own personal health, and that of their families and communities.

Reduction in caloric intake

• Calorie reduction may be the most

Exercise and physical activity

• Sedentary living is a factor in obesity during every stage of life

• Exercise and any physical activity helps to reduce the risk of obesity and leads to overall health

• Adopt an active hobby that requires exercise (gardening, dance classes, team sports, etc.)

• Long-term moderate resistance exercise improved immune system response in elderly (“Long-term, moderate exercise improves immune activity”)

• Reduce time spent engaging in sedentary behaviors like watching television

• Build physical activity into regular routines.  For example, park at the end of the parking lot and walk to a store

Education

• Learn about portion control and personal nutrition needs

• Learn to cook with fresh ingredients (packaged goods with extended shelf life often have fillers and other unhealthy ingredients)

• Talk with nutrition experts (doctors/pediatricians, teachers, physiologists and other scientists, etc.)

• Ensure school breakfast and lunch programs meet nutrition standards

• Provide all children with daily physical education and activities

Eating

• Strive to include foods with five different colors in every meal

• Abide by the USDA guidelines for fruits and vegetables (7 servings for women, 9 for men)

• Choose food options that are low in fat, calories and added sugars

• Eat slowly to give yourself time to digest your food and enable feelings of satiety to emerge

• Encourage the food industry, restaurants and fast food outlets to provide reasonable food and beverage portion sizes

• Encourage food outlets to increase the availability of low-calorie, nutritious food items

• Remove snack and soda machines from school cafeterias

Economics

• Educate low-income women about healthy weight-loss methods.   Research shows this group frequently employs maladaptive strategies for weight loss such as diet pills and purging to lose weight.  Obesity and family exposure to these behaviors places women at increased risk of unhealthy behaviors.  Education about obesity must include precautions of these unhealthy behaviors (Abstract:  “Correlates of Weight Loss Behaviors Among Low-Income African-American, Caucasian, and Latina Women” )

• Educate lower income families about the dangers of obesity and the benefits of healthy eating.  The entire family must be educated, not just the children

• Initiate programs like ENERGY (Obesity Prevention Program Aimed At Second Graders) to help children learn about nutrition, exercise and obesity to combat this epidemic

• Low-income women were more susceptible to obesity than high-income women (Abstract:  “The Burden of Disease From Undernutrition and Overnutrition in Countries Undergoing Rapid Nutrition Transition: A View From Brazil” )

• Programs addressing childhood obesity should be culturally specific and target very young children (“Childhood Overweight in a New York City WIC Population” ).