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Work Plan - Weight Management
As part of an elective offered by my medical school, I will be editing this article with evidence based medicine and well documented concepts from the medical community. I am drawn to this article because of how important diet and exercise are to not only weight management but to health overall. Initial review of this article reveals sections that primarily focus on methods and strategies for weight management. I intend to expand upon this subject by discussing the following topics (each with their own heading):

1.) the effects of calories and macronutrients on weight

2.) tracking caloric/macronutrient/micronutrient intake

3.) body composition - body fat, lean muscle mass, water weight, etc.

4.) different types of physical activity, aerobic vs. anaerobic, and how they can effect weight management

5.) The difference of weight management in children vs. adults.

I also intend to expand upon the descriptions of some of the diets in the 'Popular Diets' section. Specifically, I plan on adding information regarding risks and benefits of certain diets as they relate to certain medical conditions people might have or acquire. My primary resources will be textbooks that can be accessed through ClinicalKey and AccessMedicine. I will start my search by focusing on the fundamentals of weight management as it relates to the basics of calorie intake and physical exertion. It is crucial for the reader to understand budgeting calories in order to grasp the basics of weight management. My goal will be to focus on 1-2 of the subjects listed above each week and build comprehensive description of each of those ideas.

Given the fact that this topic is intimately interconnected with other topics like nutrition, dieting, etc., there will be ample opportunity to provide links to other articles with pertinent information in regards to weight management. With that in mind, I do not plan on including a detailed discussion of each type of macro and micro nutrient. My goal will be to expand upon this article so that it provides the tools for the reader to be able to evaluate different diets and exercise strategies and understand why certain weight management strategies affect weight loss and weight gain.

Focusing on the basic physiology of weight management is my overall objective. This may be somewhat of a difficult topic to discuss without using technical terminology but I intend on using many pictures and diagrams to illustrate the concepts. I will certainly have my peers review the article to ensure that the medical jargon is eliminated or very limited.

Key components of weight management
There are many factors that contribute to a person's weight, including: diet, physical activity, genetics, environmental factors, medications, and illnesses. Each of these factors affect weight in different ways and to varying degrees, but health professionals most often stress the importance of diet and physical activity above all other factors because they can be affected by conscious behavior modification. The following is a review of some of the key components of weight management in humans.

Energy Balance
The science behind weight management is complex, but one of the key concepts that governs weight management is Energy Balance. Energy balance is the term used to describe the difference between the number of calories a person consumes and the number of calories that same person expends (a.k.a. burns) in a given time period. There are three possible scenarios when it comes to the energy balance equation:


 * Calories consumed (food, drink) = Calories expended (basal metabolic rate, physical activity, thermogenic effect of food, acute illness)
 * Outcome: Weight remains unchanged


 * Calories consumed > Calories expended
 * Also known as Positive Energy Balance
 * Outcome: Weight increases
 * Calories consumed < Calories expended
 * Also known as Negative Energy Balance
 * Outcome: Weight decreases

The calories a person consumes come from both the foods and drinks they eat and drink. The calories a person expends comes from their basal metabolic rate and their daily physical activity. When eating a healthy diet mainly composed of vegetables, lean meats, and fruits, the human body is very good at maintaining a neutral energy balance so that calories consumed do not substantially exceed calories expended in a given time period and vice versa. This energy balance is regulated by hormones like Leptin (suppresses), Ghrelin (stimulates), and Cholecystokinin (suppresses) which either suppress or stimulate appetite. This unconscious regulation of energy balance is one of the factors that make sustained weight loss very difficult for many people. That being said, consuming fewer calories than the numbers of calories expended each day is fundamental to weight loss in both the short and long term. If attempting to loss weight, the National Heart, Lung, and Blood Institute (NHLBI) recommends a slow and steady approach by eating 500 fewer calories than the number of calories burned or expended each day.

Diet
As previously stated in the Energy Balance section above, quantity of food and drink consumed by an individual plays a very important role in weight management. Additionally, the types of food and drink a person consumes are also very important to weight management. Not only is it important to eat a well balanced diet in order to get the proper amount of vitamins and nutrients each day to prevent illness, but it is also important to be aware that certain qualities of foods and drinks (for example: energy density, palatability, sugar content) can have profound effects on weight by affecting hunger and satiety in different ways. For example, sugary drinks like sodas are very palatable and contain a significant number of calories but do little to affect satiety. In other words, drinking sugary drinks does not help get rid of hunger but still adds many calories to a person's diet which can lead to overeating, positive energy balance, and weight gain.

The United States Department of Agriculture and United States Department of Health and Human Services attempt to provide evidence based recommendations for the types and amounts of certain foods people should eat to maintain a healthy diet in a document called The Dietary Guidelines for Americans. These recommendations are updated every 5 years and the most recent version (2015-2020 Dietary Guidelines for Americans) recommends the following:

Eat a diet that is primarily composed of:


 * A diverse selection of vegetables - like dark and leafy greens, red and orange vegetables, legumes (beans and peas)
 * Whole fruits
 * Whole grains
 * Low fat and fat free dairy products - like milk, yogurt, and cheese
 * Foods high in protein like lean meats, seafood, poultry, eggs, and legumes, nuts, seeds, and soy products

Avoid or limit the following items:


 * Trans fats
 * Saturated fats - should not exceed 10% of total daily calories
 * Added sugars - should not exceed 10% of total daily calories
 * Salt - should consume less than 2,300 mg of salt per day
 * Alcohol - limited to 1 drink per day for women and 2 drinks a day for men

Some of these recommendations have been called into question since they were released; however, most health professionals agree that a diet that is primarily composed of vegetables, leans meats, whole fruits, whole grains, nuts, and seeds is ideal for maintaining a healthy weight and overall health.

Physical Activity
Physical activity is one of the main components of a person's daily energy expenditure. Physical activity can be broken down into the following types of activities:


 * Work/occupation related physical activity
 * Exercise related physical activity
 * Non-work and non-exercise related physical activity (activities of daily living)

It is important to remain physically active in all three domains listed above in order to maintain a health weight and avoid developing noncommunicable diseases like diabetes, heart disease, and dyslipidemia (high cholesterol). It can be difficult to be physically active in every area of a person's life, due to things like occupation, physical fitness level, and living environment, but increasing physical activity whenever possible can help offset times of inactivity and can lead to better weight management and overall health.

As part of the Dietary Guidelines for Americans, the United States Department of Agriculture and United States Department of Health and Human Services releases evidence based physical activity recommendations in a section titled Physical Activity Guidelines for Americans.

This section recommends the following for children (6-17 years old):


 * At least 60 minutes of physical activity per day
 * Most of their physical activity should be aerobic based with vigorous aerobic exercise 3 time per week
 * Participate in strength building physical activity 3 time per week.

This section recommends the following for adults (18-64 years old):


 * Avoid physical inactivity whenever possible
 * At least 150 minutes (2 hour and 30 minutes) of moderate intensity exercise per week OR 75 minutes (1 hour and 15 minutes) of vigorous intensity exercise per week
 * Exercise should be spread out throughout the week
 * Exercise a minimum of 10 minutes at a time
 * Progressively increase physical activity to 300 minutes (5 hours) or more of moderate intensity exercise per week OR 150 minutes (2 hours and 30 minutes) or more of vigorous intensity exercise per week
 * Participate in full body weight training exercise 2 time per week

This section recommends the following for older adults ($$\geq$$65 years old):


 * Same guidelines as adults (listed above) but modified to accommodate their level of physical fitness and chronic conditions
 * Focus on physical activity that improves balance

Basal Metabolic Rate (BMR)
Basal Metabolic rate (BMR) is one of the main components of a person's daily energy expenditure. BMR is defined as the amount of energy that is expended during a given amount of time by a person at rest. In other words, it is the amount of energy a person's body uses to do things like pump blood, maintain proper brain function, breakdown toxins, and ensure other bodily functions. Technically speaking, BMR is the amount of energy the body expends during the following very specific conditions: right after waking up, while in a resting state, and after fasting for 12-14 hours. Sometimes the term Resting Metabolic (RMR) is used in place of BMR but RMR is slightly different in that it is not measured under the previously listed stringent conditions and is about 10% more than BMR.

BMR is directly proportional to a person's lean body mass. In other words, the more lean body mass a person has, the higher their BMR. BMR is also affected by acute illnesses and increases with conditions like burns, fractures, infections, fevers, etc. BMR can be measured via direct and indirect calorimetry; however, it is possible to estimate a person's BMR using one of several equations that use a person's age, sex, height, and weight to calculate a fairly accurate estimate of a person's BMR. Some of the most popular and accurate equations used to calculate BMR are the original Harris-Benedict equations, the revised Harris-Benedict equations, and the Mifflin St. Jeor equation.

The original Harris-Benedict Equations are as follows:


 * BMR (Males) in Kcals/day = 66.47 + 13.75 (weight in kg) + 5.0 (height in cm) - 6.76 (age in years)
 * BMR (Females) in Kcals/day = 655.1 + 9.56 (weight in kg) + 1.85 (height in cm) - 4.68 (age in years)

The revised Harris-Benedict Equations are as follows:


 * BMR (Males) in Kcals/day = 88.36 + 13.40 (weight in kg) + 4.8 (height in cm) - 5.68 (age in years)
 * BMR (Females) in Kcals/day = 447.59 + 9.25 (weight in kg) + 3.10 (height in cm) - 4.33 (age in years)

The Mifflin St. Jeor Equation is as follows:


 * BMR (Males) in Kcals/day = 9.99 (weight in kg) + 6.25 (height in cm) - 4.92 (age in years) + 5
 * BMR (Females) in Kcals/day = 9.99 (weight in kg) + 6.25 (height in cm) - 4.92 (age in years) - 161

The Mifflin St. Jeor Equation was found to be the most accurate predictor of BMR compared to BMR measured by direct and indirect calorimetry.

Thermogenic Effect of Food
The thermogenic effect of food is another component of a person's daily energy expenditure and refers to the amount of energy it takes the body to digest, absorb, and metabolize nutrients in the diet. The amount of energy expended while processing food differs by individual but on average it amounts to about 10% the number of calories consumed during a given time period. Processing proteins and carbohydrates has more of a thermogenic effect than does processing fats.

Genetics
Genetics play an important role in weight management and contribute to a person's risk of becoming obese. In fact, several genes have been found to be associated with elevated Body Mass Index (BMI) and obesity. That being said, genetics can only be blamed for a small portion of a person's excess weight as there are many other significant factors that affect a person's weight, as discussed in the sections above.

There are some rare genetic disorders that do cause significant weight gain like Prader-Willi Syndrome.

Medications
Certain medications can cause either weight loss or weight gain. These side effects are often listed for each medication and should be considered when attempting to manage a person's weight.

Diseases
As previously stated, acute illnesses can effect weight management by increasing a person's BMR. There are also several other medical conditions that are associated with either weight loss or weight gain. Examples of conditions that are associated with weight gain include hypothyroidism and Cushing's Syndrome. Examples of conditions that are associated with weight loss include hyperthyroidism and many cancers.

Body Mass Index (BMI)
Body Mass Index (BMI) is a value used to get a general sense of a person's overall mass or size and is calculated using a person's height and weight. It is more often used than weight alone to determine if an individual is underweight, normal weight, overweight, or obese. The following two equations can used to calculate BMI depending on the units used for height (meters vs. inches) and weight (kilograms vs. pounds):

BMI = Weight (kg) / Height2 (m2)

OR

BMI = [ Weight (lbs) / Height2 (in2) ] x 703

Though BMI is often times used to help assess for excess weight, it is by no means a perfect representation of a person's body fat percentage. For example, an individual can have a higher than normal BMI but have a normal body fat percentage if they have higher than average muscle mass because excess muscle contributes to a higher weight. The following table shows how different ranges of BMIs are often categorized into underweight, normal weight, overweight, and obese: Since BMI is not a perfect representation of a person's body fat percentage, other measurements like waist circumference are often used to better assess for unhealthy excess weight as it pertains to body fat. Despite not being a perfect representation of healthy and unhealthy weight, BMI is very important value because it helps health professionals identify people who are at higher risk of developing illnesses like diabetes, hypertension, dyslipidemia (high cholesterol), liver disease, and some cancers. In general, as BMI increases so too does a person's risk of developing those previously stated illnesses. Additionally, regularly calculating a person's BMI can also be used to help track changes in a person's body mass over time.

INTRO Changes
Weight management is the phrase used to describe both the techniques and underlying physiological processes that contribute to a person's ability to attain and maintain a certain weight. Weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Effective weight management strategies consider not only weight loss toward but also the maintenance of a healthy body weight over time. Moreover, weight management involves developing an understanding of meaningful ways to track weight over time and to set ideal body weights for different individuals.

Proper weight management techniques does not include fad diets that promote quick, temporary weight loss. It generally focus es on the long-term results that are achieved through slow weight loss, followed by retention maintanof an ideal body weight for age, sex, and height.

Rising obesity rates are a major concern in around the world, especially in North America. About 60% of Americans and Canadians are either overweight or obese. Weight management is not just Obesity is a risk factor for many chronic diseases such as Type 2 diabetes, hypertension and cardiovascular disease. Managing one’s weight is one factor in preventing such chronic diseases.