Weight management/ja: Difference between revisions

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=== Energy balance ===

The science behind weight management is complex, but one of the key concepts that governs weight management is [[Energy homeostasis|Energy Balance]]'''.''' Energy Balance is the phrase used to describe the difference between the number of [[calorie]]s 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, [[Thermogenics|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 food and drink intake. The calories a person expends comes from their basal metabolic rate and their daily physical activity. The  human body is very good at maintaining a neutral energy balance, particularly with a diet composed of fruits, vegetables, and meats 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.

[[File:Energy drink and fast food cheeseburger calorie comparison.jpg|thumb|An image that shows nutrition label information including calorie amounts ]]

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=== Diet ===

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=== Physical activity ===

[[File:Exercise Treadmill Convey Motion.jpg|thumb|Running on a treadmill is one form of physical activity that can be done at home or at a gym.]]

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=== Basal metabolic rate ===

[[Basal metabolic rate]] (BMR) is one of the main components of a person's daily energy expenditure. It is defined as the amount of energy that is expended during a given amount of time by a person at rest. This energy at rest is used to pump blood throughout the body, maintain proper brain function, break down toxins, and ensure other bodily functions. Technically speaking, BMR is the energy the body expends during the following specific conditions: immediately 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 not solely measured under the previously listed stringent conditions and it is about 10% more than BMR.

The 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 burns, fractures, infections, fevers, etc. It can be measured via direct and indirect calorimetry. However, it is also possible to approximately estimate BMR using several equations that factor in a person's age, sex, height, and weight. Some of the most popular and accurate equations used to calculate BMR are the original [[Harris–Benedict equation|Harris-Benedict equations]], the revised Harris-Benedict equations, and the [[Mifflin-St Jeor equation|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

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=== Body mass index ===

{{Main|Body mass index}}

[[File:Obesity-waist circumference.svg|thumb|Waist circumference may be used as an alternative method to assess weight.]]

|+ Classification of Overweight and Obesity by Body Mass Index (BMI)

! Category

| Underweight

| Normal Weight

| Overweight

| Obesity (Class I)

| Obesity (Class II)

| Obesity (Class III)

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On average, groups of people with "obese" BMIs may have a higher risk of developing illnesses like diabetes, hypertension, dyslipidemia ([[Hypercholesterolemia|high cholesterol]]), liver disease, and some cancers. "Underweight" BMIs may indicate [[malnutrition]] or other health problems. However, BMI [[Body mass index#Limitations|has limitations]] when used to describe individual health rather than describing populations of people.

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== Complicating factors ==

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=== 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.

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=== Medications ===

Metanalysis has shown that [[phentermine]] and [[topiramate]], [[pramlintide]], [[Naltrexone/bupropion|naltrexone]], [[Naltrexone/bupropion|bupropion]], and [[liraglutide]] have been shown to induce weight loss. [[Semaglutide]] is another anti-obesity drug that is also used for blood sugar control.

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=== Diseases ===

Medical conditions associated with weight gain include [[hypothyroidism]], [[Cushing's syndrome]], [[Polycystic ovary syndrome|Polycystic Ovary Syndrome (PCOS)]], and congestive heart failure. Medical conditions such as [[cancer]], gastrointestinal illness, psychiatric disorders, infections, endocrine disorders, and neurologic disorders may lead to weight loss.

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==== Commonly associated with weight gain ====

Polycystic ovary syndrome (PCOS), which is characterized by [[insulin resistance]] and [[hyperandrogenism]], is a common condition that has been linked to obesity. A combination of genetics, lifestyle, and environment appear to contribute to the hormonal changes responsible for weight gain and obesity seen in individuals with PCOS. There appears to be a bidirectional relationship between obesity and PCOS, whereby PCOS increases the risk of obesity and similarly, obesity has been found to exacerbate PCOS hormonal differences and clinical symptoms.

Obesity has been linked with pancreatic [[Beta cell|β-cell]] dysfunction and insulin resistance. In diabetes, impaired β-islet cells are responsible for the lack of blood glucose control. Individuals with a higher body mass index concerning for obesity may have increased levels of hormones, proinflammatory markers, and glycerol, which can contribute to insulin resistance. The combined effects of impaired pancreatic β-islet cells and insulin resistance increase the likelihood of developing diabetes.

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==== Commonly associated with weight loss ====

Common gastrointestinal disorders associated with weight loss are malabsorption due to [[Coeliac disease|Celiac disease]] or [[chronic pancreatitis]]. [[Depression (mood)|Depression]] and eating disorders such as [[anorexia nervosa]] can also contribute to weight loss. Infectious causes of weight loss include [[HIV/AIDS]].

While [[Type 1 diabetes]] has been found to cause weight loss, type 2 diabetes has been associated with weight gain. Other endocrine causes of weight loss include [[hyperthyroidism]] and [[chronic adrenal insufficiency]].

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==Intentional weight loss==

===Diets===

{{See also|List of diets}}

As weight loss depends partly on [[calorie]] intake, different kinds of [[Calorie restriction|calorie-reduced]] diets, such as those emphasizing particular macronutrients ([[low-fat diet|low-fat]], [[low-carbohydrate diet|low-carbohydrate]], etc.), have been shown to be equally effective as weight loss tools. Nonetheless, a low-saturated fat diet complemented with high fiber can be helpful for those who are found to be obese based on BMI. Furthermore, a low-carbohydrate diet can have the added benefits of blood sugar control in those with [[Type 2 diabetes|Type 2 Diabetes Mellitus.]] A low-carbohydrate diet can also improve weight loss, [[High-density lipoprotein|HDL]], and cholesterol in certain individuals. Compared to a typical diet, low-carbohydrate, low-fat, and moderate macronutrient diets can all positively impact weight loss. However, weight regain is common, and the outcome of a diet can vary widely depending on the individual. Rather than focusing on the nuances of each diet type, molding one diet in a way that the person can continuously adhere in the long-term could be beneficial for weight loss.

;DASH diet

The [[DASH diet|Dietary Approaches to Stop Hypertension (DASH) diet]] focuses on increasing the consumption of fruits, vegetables, whole grains and low-fat dairy products. DASH offers an intervention to manage elevated blood pressures and prevent cardiovascular disease non-pharmacologically. In addition, combining the DASH diet with a reduced sodium intake will further decrease blood pressure, but is not required for therapeutic effect. This is because it has been proven to be effective at a wide range of sodium intake levels. More recent reviews of DASH have continued to advocate its efficacy as an affordable weight loss tool, but stress that diet adherence is key to produce the desired results.

[[File:DIETA MEDITERRANEA ITALIA.JPG|thumb|Fruits and vegetables are considered staples of the Mediterranean diet.]]

;Mediterranean diet

The [[Mediterranean diet]] involves eating fruits, vegetables, whole grains and beans while replacing butter with extra-virgin olive oil and limiting red meats, dairy, sweets, and processed foods. It has been shown to be effective for long term weight loss with added cardiovascular health benefits. For example, the Mediterranean diet can lead to decreased triglyceride and lipid levels as well as improved blood pressure readings. It can also improve blood sugar levels in those diagnosed with Type 2 Diabetes Mellitus.

;Ketogenic diet

The [[Very low-carbohydrate ketogenic diet|ketogenic]] or "keto" diet involves intake of less than 50 g of carbohydrates daily along with increased fat and protein amounts. One type of ketogenic or low carbohydrate diet is the "Atkins" Diet, which does not restrict protein and fat amounts. However, there are other ketogenic diets that place restrictions on the total amount of daily proteins and fats.

;Plant-based diet

The [[plant-based diet]] is largely based on consumption of beans, grains, fruits, and vegetables and removal of meat, fish, and occasionally dairy and egg products from intake. In other words, fiber and unsaturated fat intake is increased and consumption of higher calorie meats and saturated fats is decreased. This diet has been shown to reduce BMI and introduce positive body composition changes when compared to a carnivore diet.

;Intermittent fasting

[[Intermittent fasting]] (IF) involves consistent fasting blocks of time where fewer or no calories are consumed. Intermittent fasting has been shown to improve fasting blood glucose levels and insulin resistance with a concurrent reduction in BMI.

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=== Strategies ===

[[File:Dinner meal - MyPlate 20210810-FNS-UNC-0017.jpg|thumb|An dinner example of portion sizes relative to food groups ]]

==== Modifying plate size ====

Some studies have suggested that using smaller plates might help people to consume smaller [[portion size]]s.

Modifying portion sizes may impact energy intake. Those who are presented with larger portion sizes do not report to have high levels of satiety. In other words, hunger and satiety signals could be ignored with large portion sizes. In a study focused on portion sizes, participants consumed 31% less calories with the small portion sized of a 6-inch [[submarine sandwich]] compared with the large portion size of a 12-inch submarine sandwich. Increased portions have occurred simultaneously with the increase in [[obesity]] rates. Large portion sizes could be one of the factors contributing to the current increase in average body weight in the US. Evidence from a [[systematic review]] of 72 [[randomized controlled trials]] indicates that people consistently eat more food when offered larger portion, package, or tableware sizes as opposed to smaller size alternatives.

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==== Choosing low-calorie foods ====

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==== Increasing protein intake ====

A high [[protein]] diet relative to a low-fat or high-carbohydrate diet may increase [[thermogenesis]] and decrease [[appetite]] leading to weight reduction, particularly 3-6 months into a diet when rapid weight loss is observed.  However, these advantages may be reduced later at 12–24 months into a diet during the slow weight loss phase.

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==== Eating more soup ====

==== Eating more dairy ====

[[File:Glass of milk on tablecloth.jpg|thumb|Milk intake has been advocated as a weight loss strategy due to its calcium and other nutrients. ]]

Studies have shown that a diet high in dairy decreases total body fat. This occurs because a high amount of dietary calcium increases the amount of energy and fat excreted from the body.  Other studies have noted that dairy sources of calcium lead to greater weight loss than supplemental calcium intake. This could be due to the bioactive components of dairy sources, especially when combined with a lower calorie diet. Since most natural dairy products contain fat content, there is a common understanding that this may cause weight gain. However, dairy contains ingredients such as [[Whey protein isolate|whey protein]] and certain combinations of protein/calcium nutrients that induce a positive effect on satiety, increase energy loss, and assists weight loss.

==== Eating more vegetables ====

Fruits and vegetables have been shown to increase satiety and decrease hunger signals. These food groups have a low energy density, mainly due to the high [[water content]] and partly due to the [[Dietary fiber|fiber]] content. The reduction of energy density has been shown to enhance satiety. The water content adds satisfying weight without excess calories and fiber slows gastric emptying. Studies have also shown that fiber decreases hunger and also decreases total energy intake.

==== Increasing fiber intake ====

Fruits and vegetables are two sources of fiber as discussed above. [[Dietary fiber]] has been suggested to aid weight management by inducing satiety, decreasing absorption of [[macronutrients]] and promoting secretion of gut hormones. Dietary fiber consists of non-digestible carbohydrates and [[lignin]], which are a structural component in plants.

[[File:Foods.jpg|alt=Fruits and vegetables contain a natural source of fiber that can lead to improved satiety.|thumb|Fruits and vegetables contain fiber which has been shown to improve satiety and help with weight loss. ]]

Due to the high volume or water content of fiber-rich foods, fiber displaces available calories and nutrients from the diet. Consumption of viscous fibers delays gastric emptying, which may cause an extended feeling of fullness. Satiety is also induced by increasing chewing, which limits food intake by promoting the secretion of [[saliva]] and [[gastric juice]], resulting in an expansion of the stomach. In addition, hormone secretion is affected during fiber ingestion. Insulin response is reduced and [[cholecystokinin]] (CCK) in the small intestine is increased. Insulin regulates [[blood glucose]] levels while CCK adjusts gastric emptying, [[pancreatic]] secretion, and [[gall bladder]] contraction. There is a direct correlation between CCK and satiety after foods of different fiber contents are consumed.

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==== Increasing resistant starch intake ====

Resistant starch is a type of non-digestible, [[Fermentation (food)|fermentable fiber]] resistant to [[amylase]] digestion in the [[small intestine]]. It is broken down to [[short-chain fatty acid]]s by [[microflora]] in the [[large intestine]]. It is commonly found in cooked and cooled potatoes, green bananas, beans and legumes. The short chain fatty acids can lead to further oxidation of fat and a higher energy expenditure. Resistant starch dilutes energy density of food intake, maintains a bulking effect similar to non-fermentable fiber, and increases the expression of gut hormones [[Peptide YY|PYY]] and [[Glucagon-like peptide-1|GLP-1]]. The increase in gut hormone expression affects neuronal pathways in the brain that contribute to long-term energy balance and improved overall health of the [[intestines]].

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==== Increasing caffeine intake ====

[[Caffeine]] and black [[coffee]] have been associated with increased energy expenditure and subsequent weight loss. Caffeine belongs to a class of compounds called [[methylxanthines]] and is present in coffee, tea, cocoa, chocolate and some cola drinks. Caffeine induces a [[Thermic effect of food|thermogenic effect]] in the body by increasing [[sympathetic nervous system]] activity, which is an important regulator of energy expenditure.

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==== Increasing green tea intake ====

[[File:Health benefits of green tea.png|thumb|Green tea contains catechins that may aid weight loss. ]]

Catechins are [[tea polyphenol|polyphenols]] that are a major component of green tea extract. [[Green tea]] has been associated with decreasing blood glucose, inhibiting [[hepatic]] and body fat accumulation, and stimulating thermogenesis due to the [[Tea catechins|catechins]] present in formulations. Moreover, catechins in the brain play a major role in satiety. Independent of the caffeine content, green tea has also been shown to increase energy expenditure and fat oxidation in humans.