Obesity rates continue to rise across the United States. In fact, the Centers for Disease Control and Prevention (CDC) currently estimates that more than 35% of American adults are obese, and about 17% of children and adolescents are obese.

Numerous health risks are linked to obesity. They comprise some of the most common preventable causes of death, including coronary heart disease, type II diabetes mellitus, and strokes. In 2008, medical costs associated with obesity were estimated at $147 billion. Efforts to decrease obesity among adults and children are crucial from a public health standpoint.

Current Physical Activity Guidelines recommend 150 minutes (or about 30 minutes, five times a week) of moderate to vigorous physical activity per week. Specifically for weight loss purposes, many experts recommend longer durations of exercise - up to 60 minutes per day.

Are these longer periods of exercise necessary for optimal weight loss? Does the extra time increase fat loss? Or is there a compensation effect whereby the body adjusts to the additional exercise?

In a paper published recently in the American Journal of Physiology, studied this question using samples of overweight, sedentary men. The authors compared a group which performed 30 minutes of daily aerobic exercise for 13 weeks to one which performed 60 minutes per day.

The authors compared the groups based on body fat loss, as well negative accumulated energy balance, which they calculated from the changes in body composition.

Participants who performed 30 minutes of aerobic exercise per day experienced the same amount of body fat loss compared to those who performed 60 minutes per day. Surprisingly, the overweight men who exercised 30 minutes per day had a much greater than predicted negative energy balance. There was no additional benefit obtained by doing 60 minutes of exercise per day.

The authors concluded that while one group of overweight men performed twice the amount of daily aerobic exercise, the decrease in body weight and body fat was no greater than the group that performed half as much.

This study provides good news to overweight individuals who want to start an exercise regimen to lose weight and body fat. Since many of these people do not regularly exercise, starting with 30 minutes per day might be more appealing. They might be more likely to stick to the shorter programs.

When it comes to obesity and weight loss, any exercise seems better than none at all. While we need much more research to find ideal nutritional changes and specific exercise recommendations, Americans of all ages can at least start with moderate amounts of exercise each day.

What do you think about this study and its findings? Will it make you more likely to try to perform physical activity each day?

Childhood obesity has become a public health concern in recent years. The Centers for Disease Control and Prevention estimates that approximately 12.5 million children and adolescents are obese. This number accounts for approximately 17% of children and adolescents between the ages of 2 and 19 in the United States. Worse, it estimates that the obesity rate among children and adolescents has tripled since 1980.

Many factors likely play a role in the trend for increasing childhood obesity in the United States. These factors include the consumption of fast food and soft drinks, lack of physical activity, and increased time spent watching television or playing video games.

While preaching better nutrition and physical activity to kids is essential, that message will likely prove far more effective if parents serve as better examples of good health.

What can parents do to lead healthy lifestyles and demonstrate those lifestyle behaviors to their children?

Teach better nutrition

Not only should kids eat healthier foods and drink healthier beverages, they should also learn to make better nutritional choices themselves. Getting rid of junk food and soft drinks can be good start for a healthier family, but children should learn how to choose healthier foods and beverages.

One idea that parents can consider for instilling proper nutrition involves taking the kids to the grocery store. Walk up and down the aisles and teach them why certain foods are more nutritious than others. Then allow them to select some of the foods and drinks themselves, perhaps for a family meal. If they can bring their own lunches to school, allow them to choose foods for their daily lunches.

By teaching nutrition at an early age, it's more likely these youth will make healthier food choices as they get older and more independent.

Limit screen time

The amount of time that kids spend staring at a screen is staggering. When parents consider how much time their children perform these activities, they need to consider how often their kids spend time watching TV, using computers, playing video games, watching movies, or looking at cell phones.

Studies show that kids between the ages of 8 and 18 watch television for an average of 4.5 hours per day. When other forms of screen time are included, this average jumps to 7.5 hours per day.

This screen time can increase the chances that a child becomes obese. Kids are likely to snack, especially on junk food, while watching TV. Also, these young kids will likely see hundreds of advertisements for unhealthy foods and beverages during the television programs. More importantly, some of that 7.5 hours could be spent engaging in regular physical activity.

The American Academy of Pediatrics recommends that parents limit their children's total media consumption to no more than one to two hours per day. While this guideline is critical for children and adolescents to follow, parents should use it as well. It is hard to preach limits on screen time if the parents come home and watch TV too.

Engage the family in physical activity

The 2008 Physical Activity Guidelines for Americans recommends that children and adolescents perform at least 60 minutes of physical activity each day. Parents can play a large role in helping their kids achieve these daily recommendations by engaging them in fun activities involving physical exertion. Jogging, walking, taking bike rides, hiking, and many other activities can be both fun and physically beneficial. To keep the kids enthusiastic about exercise, allowing them to bring their friends or encourage them to pick the activities.

If children see their parents exercising regularly, they are also more likely to accept it as a normal part of their own lives. They might look forward to exercising rather than perceiving it as some sort of punishment.

If parents commit to becoming healthier themselves - making better nutrition choices and performing regular physical activity - their children are much more liekly to emulate these behaviors.

What are you doing to engage your family in fitness?

Sports participation in the United States has reached record levels, and high school-level sports participation continues to rise. In fact, the National Federation of State High School Associations estimates that more than 7.6 million high school students (over 55% of all students) played sports during the 2010-2011 academic year.

As orthopaedic surgeons, we are all too familiar with injuries that can occur in sports. But the benefits far outweight the potential for injury. Since we are wrapping up National Physical Fitness and Sports Month, the American Orthopaedic Society for Sports Medicine would like to focus on the many positive benefits of sports - and encourage Americans to participate.

The physical benefits of competitive sports are the most obvious. Much attention has been given to the role of sports and exercise in decreasing the rates of obesity in our nation's youth. While lower body mass among athletes is certainly a desirable marker, it is not the only purported advantage of the regular exercise that comes with sports participation. Athletes experience lower rates of diabetes and high blood pressure, as well as improved cardiovascular and pulmonary function.

However, the benefits of sports are not simply limited to physical health. Here are just a few reasons to consider playing sports or encouraging your children to play sports.

Social Benefits

A study published in Pediatric and Adolescent Medicine reported that out of 14,000 high school atheletes, the ones who regularly played sports were less likely to use drugs. Likewise, a survey performed by the National Household Survey of Drug Abuse showed that students who played sports were less likely to have smoked cigarettes or used drugs and were more likely to disapprove of others using them. Also, the Women's Sports Foundation has stated that female high school athletes are 80% less likely to become pregnant than non-athletes. 

Academic Benefits

Studies perfomed among students in multiple states - including Wyoming, Iowa, and Colorado - have shown that playing sports can actually increase success in the classroom. Various data demonstrate that athletes have higher grade point averages, higher standardized test scores, better attendance, lower dropout rates, and a better chance of going to college.

Career Benefits

A survey of individuals at the level of executive Vice President of 75 Fortune 500 companies showed that 95% of them played sports in high school. While it might be hard to argue that sports participation could guarantee higher incomes, promotions, and better jobs, the leadership skills and development of teamwork, hard work, and determination might help prepare students to be leaders at work and in their communities later in life.

While it is important for adults to be aware of the risks of injuries in various sports, both for themselves and for their kids, it is important to remember that there are many great reasons to play them as well! How are you encouraging your family and friends to get involved in sports?