Weight, Obesity, Fitness and Health

With shift work, weight gain seems almost unavoidable- perhaps even more reliable than a weekly paycheck. Behind us are our genes, programmed in times of hunting and gathering to push us to see food, grab it, and devour it, since who knows when another fruit tree or dead animal fall into our laps? In front of us living in the 21st century is McDonalds, Dairy Queen, Sonic, Burger King, huge supermarkets, big plates and silverware, lattes, breakfast muffins, cars to carry us from one place of food to another. Furthermore, shift work makes time for exercise difficult. Night shifts sleep, which can cause the body to hang on to extra weight. It’s no wonder obesity has become such a problem. Many news articles talk about the problem, but how can you determine your risk level and what plan of action is right for you?


Obesity continues to be a health concern for adults, children and adolescents world-wide. The prevalence of obesity in U.S. adult men was 33.3% in 2005-2006. Among U.S. adult women, the prevalence of obesity in 2005-2006 was 35.3%. And, in 2006, 16.3% of U.S. children and adolescents aged 2-19 years were obese. According to the World Health Organization, globally there are more than 1 billion overweight adults, at least 300 million of them obese.

Obesity has been thought to increase the risk of many diseases and health conditions (e.g. hypertension, Type 2 diabetes, coronary heart disease, stroke, gallbladder disease, sleep apnea and some cancers). However, some recent studies have indicated that many overweight and obese people are actually metabolically healthy.

For example, according to one study, some obese individuals do not appear to have an increased risk for heart disease, while some normal-weight individuals experience a cluster of heart risks. In this study, researchers from the Albert Einstein College of Medicine, Bronx, N.Y. reviewed body weight and the prevalence of cardiometabolic abnormalities in 5,440 individuals participating in the National Health and Nutritional Examination Surveys between 1999 and 2004. Abnormalities included high blood pressure, high triglyceride levels and lower good cholesterol levels (levels of high-density lipoprotein). Participants were considered metabolically healthy if they had none or only one abnormality and metabolically abnormal if they had two or more abnormalities.

The study found that among U.S. adults 20 years and older, 51.3% of overweight adults were metabolically healthy and 31.7% of obese individuals were metabolically healthy, while 23.5% of normal-weight individuals were metabolically abnormal. Normal-weight adults with metabolic abnormalities tended to be older, less physically active and have larger waists than healthy normal-weight individuals. Obese individuals with no metabolic abnormalities were more likely to be younger, black, be more physically active and have smaller waists than those with metabolic risk factors. Overall, thin people were still metabolically healthier than people who were overweight or obese.

The study authors caution that “Further studies into the behavioral, hormonal or biochemical and genetic mechanisms underlying these differential metabolic responses to body size are needed and will likely further the identification of possible obesity intervention targets and improve cardiovascular disease screening tools.”

Historically, obesity, as measured using the following two primary tools, has been seen as a significant predictor of poor health:

  • 1. First, body mass can be calculated; Body Mass Index (BMI) measures weight in proportion to height. A normal B.M.I. ranges from 18.5 to 25. Once B.M.I. reaches 25, a person is viewed as overweight. Thirty or higher is considered obese. See BMI calculations by The Center for Disease Control @ http://www.cdc.gov/nccdphp/dnpa/healthyweight/assessing/bmi/index.htm.
  • 2. Second, waist circumference can be measured. To measure waist circumference, place a tape measure around the abdomen just above the hip bone. Make sure the tape is tight but not compressing the skin, exhale breath and measure.

In December 2007, a study published in The Journal of the American Medical Association looked at death rates among 2,600 adults 60 and older over 12 years. This study found that fitness level, regardless of body mass index, was the strongest predictor of mortality risk. Those with the lowest level of fitness, as measured by the treadmill tests, were four times as likely to die during the 12-year study as those with the highest level of fitness. Even participants who had just a minimal level of fitness had half the risk of dying compared with those who were least fit. During the test, the treadmill moved at a brisk walking pace as the grade increased each minute. In the study, it didn’t take much to qualify as fit. For men, it meant staying on the treadmill at least 8 minutes; for women, 5.5 minutes. People falling below those levels, whether fat or thin, were at highest risk. The results were adjusted to control for age, smoking and underlying heart problems. Even among older participants, those who smoke and those with heart problems, fitness, not weight, was most important in predicting mortality risk.

The study also found that death rates among the overweight, those with a B.M.I. of 25 to 30, were slightly lower than in normal weight adults. Death rates were highest among those with a B.M.I. of 35 or more.

Research has indicated that in addition to overall obesity, the way body fat is distributed may influence risk for heart disease and diabetes. It is believed that individuals with fat within the abdominal cavity, estimated by measuring waist size, may be at higher risk for insulin resistance (a pre-diabetic condition that occurs when the body fails to respond to the hormone insulin) and for having an unhealthy cardiovascular risk profile.

In another study, researchers at the University of Tabingen, Germany, studied 314 individuals age 18 to 69 (the average age was 45). The researchers measured participants’ total body fat, visceral fat (abdominal fat around internal organs) and subcutaneous fat (fat under the skin). Participants were divided into four groups: normal weight, overweight, obese but sensitive to insulin and obese with insulin resistance.

Both obese groups and the overweight group had more total body and visceral fat than those at a normal weight. However, the study found that obese individuals with insulin resistance had more fat within their livers and skeletal muscles than obese individuals without insulin resistance. And, obese participants in the insulin-resistant group had thicker walls in their carotid arteries, an early sign of narrowing of the arteries, a heart disease risk factor.

Individuals in the obese-insulin sensitive group did not differ from the normal-weight group in insulin sensitivity or artery wall thickness. The authors defined these participants as having benign obesity. They concluded that fat accumulation in the liver may be more important than visceral fat in assessing cardiovascular risk.

If fat accounts for more than 5 or 10% of the liver’s weight, then a person is diagnosed as having steatohepatitis, often referred to as fatty -liver or silent liver diseas. Haeving a fatty liver produces no symptoms on its own, so people often learn they have fatty liver when they have medical tests for other reasons. Having a fatty liver can damage a person’s liver for years or even decades without the person even knowing about it. Eventually as the disease gets worse, the person may experience fatigue, weight loss, abdominal discomfort, weakness and confusion.

Eating excess calories causes fat to build up in the liver. When the liver does not process and break down fats as it normally should, fat accumulates. People tend to develop fatty liver if they have other conditions, such as obesity, diabetes, or high triglycerides. Alcohol abuse, rapid weight loss and malnutrition can also lead to fatty liver. However, some people develop fatty liver even if they have none of these conditions.

According to the National Institute for Health (NIH), there are no specific treatments for fatty liver. The most important recommendations given to persons with this disease are to reduce their weight (if obese or overweight), follow a balanced and healthy diet, increase physical activity, avoid alcohol and avoid unnecessary medications.

Fitness Recommendations for All Ages

For Adults – On May 14, 2008, The President’s Council on Physical Fitness and Sport announced a new fitness test for adults. The adult test is similar to the physical fitness test offered for children between the ages of 6 and 17. The adult fitness test examines the following health related fitness components:

  • Aerobic Fitness: measures the ability of the heart and lungs to deliver blood to muscles. This activity is tested with a 1 Mile Walk or a 1.5 Mile Run.
  • Muscular Strength and Endurance:  tests whether participant has enough strength and endurance to perform normal activities easily and while protecting the lower back. This activity is tested with the Half Sit-Up and Push-Ups.
  • Flexibility:  measures the ability to move joints through their proper range of motion. This activity is tested with the Sit and Reach test.
  • Body Composition:  measures body fat, especially around the waist. This activity is tested with Body Mass Index (BMI).

Each participant can enter their data online at the online Adult Fitness Test, which gives each participant a FITT score. The FITT score will provide each participant methods to improve in Frequency, Intensity, Time, and Type of activities.

For older adults and seniors – the NIH recommends four types of exercises:
1.  Strength exercises to maintain and build muscles and increase metabolism which helps to control weight and blood sugar levels.
2. Balance exercises to maintain and increase leg muscles which can prevent falls. According to the NIH, U.S. hospitals have 300,000 admissions for broken hips each year, many of them seniors; falling is often the cause of those fractures.
3. Stretching exercises to provide more freedom of movement.
4. Endurance exercises, such as walking, jogging, swimming, biking, even shoveling snow or raking leaves to improve heart rates and breathing capacity.

For Children and Teens – According to the 2005 dietary guidelines from the U.S. Department of Agriculture (USDA) and the Department of Health and Human Services (HHS), all children 2 years and older should get at least 60 minutes of moderate to vigorous exercise each day. Instead, according to the American Academy of Pediatrics (AAP), the average child is watching about 3 hours of television a day. To get children to be more active, limit the amount of time they spend in sedentary activities, like watching television or playing video games. The AAP recommends that children under the age of 2 years watch no TV at all and that screen time should be limited to no more than 1 to 2 hours of quality programming a day for kids 2 years and older. Encourage kids to use TV/video game time to play Dance Dance Revolution, Wii Sports or Wii Fit.

Generally, kids don’t do as well with formal exercise programs. They do best with active free play like tag, capture the flag or catch and organized team and individual youth sports.

Impact on Shift Workers

Participation in shift work has been associated with increased body mass index, prevalence of obesity and other health problems. Shift work often decreases opportunities for physical activity and participation in organized sports. For those shift workers who are able to exercise, exercise often occurs at unusual and varying times of day. Longer term adherence to an exercise program can be negatively impacted. Sleep deprivation also negatively impacts the long term adherence to an exercise program.

Eating regular, healthy, routine meals is often challenging when working shift work. Meal frequency is reduced and snacking is often increased when people work the night shift. Often this is due to the unavailability of healthy foods in the workplace, a lack of time, and a reduced desire to eat at night. Normal family eating habits are also disrupted. The metabolic responses to food are also altered by shift work-related disruptions to sleep and circadian rhythms.

In short, shift workers have to pay attention to how their work shift impacts eating habits, exercise routines and sleep patterns. By properly managing these everyday behaviors, shift workers can make work/lifestyles a healthy way of life.


This material is provided for personal, non-commercial, educational and informational purposes only and does not constitute a recommendation or endorsement

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