肥満の管理

肥満の管理には、生活習慣の改善、薬物療法、手術などがある。多くの研究が効果的な介入を模索しているが、現在のところ、エビデンスに基づいた、明確に定義された、効率的な肥満予防介入はない。

肥満の治療は、しばしば健康的な栄養による減量と身体運動の増加からなる。 2007年のレビューでは、2型糖尿病の患者や減量を受けた女性などの特定のサブグループは、全死因死亡率において長期的なベネフィットを示すが、男性の長期的な転帰は "明確ではなく、さらなる調査が必要である"と結論づけている。

肥満に対する最も効果的な治療は肥満手術である。重度の肥満に対する手術は、長期的な体重減少と全死亡率の低下と関連している。ある研究では、標準的な減量法と比較した場合、10年後の体重減少が14％～25％（実施した手術の種類によって異なる）、全死因死亡率が29％減少した。また、別の研究では、重度の肥満に対して肥満手術を受けた人の死亡率が減少している。

2021年6月、米国食品医薬品局（FDA）は、成人の長期体重管理薬として、「ウゴービ」の商品名で販売されているセマグルチド注射剤を承認した。軽度の胃腸の副作用とともに6～12％の体重減少を伴う。

もう1つの薬物であるオルリスタットは広く入手可能であり、長期使用が承認されている。その使用により、1～4年後に平均2.9kgという緩やかな体重減少が得られるが、これらの薬が肥満の長期合併症にどのような影響を及ぼすかについての情報はほとんどない。その使用は高い確率で胃腸の副作用と関連している。

食事療法プログラムは短期的な体重減少をもたらすことができ、長期的にはそれほどでもない。不当な扱いを受けている集団を含め、より大きな体重減少の結果が得られるのは、適切な栄養摂取を定期的に身体運動やカウンセリングと組み合わせた場合である。食事および生活様式の変化は、妊娠中の過度の体重増加を制限するのに有効であり、母子ともに転帰を改善する。

ダイエット

詳細は「ダイエット」を参照

BMIに基づく治療選択

治療	25-26.9	27-29.9	30-34.9	35-39.9	≥40
生活習慣への介入 （食事、身体活動、 行動）	Yes	Yes	Yes	Yes	Yes
薬物療法	非適用	併存疾患を有する	Yes	Yes	Yes
手術	非適用	非適用	非適用	併存疾患を有する	Yes

減量を促進するための食事療法は、4つのカテゴリーに分けられる： 低脂肪、低炭水化物、低カロリー、超低カロリーである。多くの食事パターンが有効である。6つのランダム化比較試験のメタアナリシスでは、主なダイエット法の3つのタイプ（低カロリー、低炭水化物、低脂肪）に違いはなく、すべての研究で2～4kgの体重減少が見られた。 2年後には、これら3つの方法は、強調された大栄養素に関係なく、同様の体重減少をもたらした。高タンパク質食では違いはないようである。清涼飲料水に含まれるような加糖の多い食事は体重を増加させる。ダイエット単独でも、肥満者の体重減少や健康増進に効果があるという証拠がある。しかし、成人を対象とした大規模な研究では、肥満が脳構造の違いと関連していることが明らかになったが、その主な原因は遺伝的要因の共有であった。このことは、肥満に対する介入はエネルギー量だけに焦点を当てるのではなく、肥満が遺伝的に関連している神経行動学的プロファイルも考慮に入れるべきであることを示唆している。

カロリー制限のためのダイエットは、アメリカ人のための食事ガイドラインやイギリスのNICEによって、太りすぎの人に勧められている。

運動

「Physical exercise/ja」も参照

筋肉は使用によって、脂肪とグリコーゲンの両方からエネルギーを消費する。脚の筋肉は大きいため、ウォーキング、ランニング、サイクリングは体脂肪を減らすのに最も効果的な運動手段である。運動は多量栄養素のバランスに影響する。早歩き程度の適度な運動では、燃料として脂肪をより多く使用するように変化する。健康維持のために、アメリカ心臓協会は少なくとも週5日、30分以上の適度な運動を推奨している。

コクラン共同計画は、運動だけでは体重減少に限界があることを明らかにした。しかし、食事療法との併用では、食事療法のみよりも1 kgの体重減少をもたらした。運動の程度が大きいほど、1.5kgの減量が観察された。 一般集団で行われる運動はわずかな効果しかないにもかかわらず、用量反応曲線が見られ、非常に激しい運動は大幅な体重減少につながる。食事制限のない20 週間の基礎軍事訓練で、肥満の軍新兵は12.5kg減量した。 体重減少を維持するには、高レベルの身体活動が必要なようだ。 モチベーションを高めるには歩数計が有効であるようだ。平均18週間の使用で、身体活動が27％増加し、BMIが0.38減少した。

階段の利用を奨励する標識や地域キャンペーンは、住民の運動を増やすのに効果的であることが示されている。 例えば、コロンビアボゴタ市では、毎週日曜日と祝日に113kmの道路を封鎖し、市民が運動しやすいようにしている。こうした歩行者天国は、肥満を含む慢性疾患と闘うための努力の一環である。

In an effort to combat the issue, a primary school in Australia instituted a standing classroom in 2013.

There is evidence that exercise alone is not sufficient to produce meaningful weight loss, but combining dieting and exercise provide the greatest health benefits and weight loss on the long term.

Weight loss programs

Weight loss programs involve lifestyle changes including diet modifications, physical activity and behavior therapy. This may involve eating smaller meals, cutting down on certain types of food and making a conscious effort to exercise more. These programs also enable people to connect with a group of others who are attempting to lose weight, in the hopes that participants will form mutually motivating and encouraging relationships. Since 2013, the United States guidelines recommend treating obesity as a disease and actively treat obese people for weight loss.

A number of popular programs exist including Weight Watchers, Overeaters Anonymous and Jenny Craig. These appear to provide modest weight loss (2.9kg) over dieting on one's own (0.2kg) over a two-year period, similarly to non-commercial diets. As of 2005, there was insufficient scientific evidence to determine whether Internet-based programs produce effective weight loss. The Chinese government has introduced a number of "fat farms" where obese children go for reinforced exercise and has passed a law which requires students to exercise or play sports for an hour a day at school (see Obesity in China).

In a structured setting with a trained therapist, these interventions produce an average weight loss of up to 8 kg in 6 months to 1 year, and 67% of people who lost greater than 10% of their body mass maintained or continued to lose weight one year later. There is a gradual weight regain after the first year of about 1 to 2 kg per year, but on the long-term this still results in weight loss. Risk factors for cardiovascular disease and for diabetes are reduced for several years after taking part in a weight management programme, even if people regained weight.

Attending group meetings for weight reduction programmes rather than receiving one-on-one support may increase the likelihood that obese people will lose weight. Those who participated in groups had more treatment time and were more likely to lose enough weight to improve their health. Study authors suggested that one explanation for the difference is that group participants spent more time with the clinician (or whoever delivered the programme) than those receiving one-on-one support.

Comprehensive diet programs, providing counseling, targets for calorie intake and exercise, may be more efficient than dieting without guidance ("self-help"), although the evidence is very limited. Following comprehensive lifestyle modifications, the average maintained weight loss is more than 3kg or 3% of total body mass, and could be sustained for five years, and up to 20% of the individuals maintain a weight loss of at least 10% (average of 33 kg). There is some evidence that fast weight loss produce greater long-term weight loss than gradual weight loss. Moderate on-site comprehensive lifestyle changes produce a greater weight loss than usual care, of 2 to 4 kg on average in 6 to 12 months. High-intensity comprehensive programs usually yield more weight loss than moderate or low-intensity, with about 35% to 60% of overweight individuals maintaining more than 5 kg weight loss after 2 years.

The NICE devised a set of essential criteria to be met by commercial weight management organizations to be approved.

The Transtheoretical Model (TTM) has been used as a framework to assist the design of lifestyle modification programmes, including weight management. A systematic review found that there is insufficient evidence to draw conclusions regarding the effects of TTM-based programs targeting weight loss that included dietary or physical activity interventions, or both (and also combined with other interventions), on sustainable weight loss (one year or longer) in overweight and obese adults. However, very low quality evidence points that this approach may induce positive changes in physical activity and dietary habits, such as increased in exercise duration and frequency, improvement in fruits and vegetables consumption, and reduced dietary fat intake.

Medication

Main article: Anti-obesity medication

Orlistat (Xenical), the most commonly used medication to treat obesity and sibutramine (Meridia), a withdrawn medication due to cardiovascular side effects

Anti-obesity medications currently approved by the FDA for weight loss

Several anti-obesity medications are currently approved by the FDA for long term use.

• Semaglutide (Wegovy) is currently approved by the FDA for long-term use, being associated with a 6-12% loss in body weight compared to placebo.
• The combination drug phentermine/topiramate (Qsymia) is approved by the FDA as an addition to a reduced-calorie diet and exercise for chronic weight management.
• Orlistat reduces intestinal fat absorption by inhibiting pancreatic lipase. Over the longer term, average weight loss on orlistat is 2.9kg. It leads to a reduced incidence of diabetes, and has some effect on cholesterol. However, there is little information on how it affects the longer-term complications or outcomes of obesity.
• Racemic amphetamine, phendimetrazine, diethylpropion, and phentermine are approved by the FDA for short term use.

Other medications

• Bupropion, topiramate, and zonisamide are sometimes used off-label for weight loss.
• The usefulness of certain drugs depends upon the comorbidities present. Metformin is preferred in overweight diabetics and for those gaining weight because taking clozapine for schizophrenia, as it may lead to mild weight loss in comparison to sulfonylureas or insulin. The thiazolidinediones, on the other hand, may cause weight gain, but decrease central obesity. Diabetics also achieve modest weight loss with fluoxetine and orlistat over 12–57 weeks.
• Rimonabant (Acomplia), another drug, had been withdrawn from the market. It worked via a specific blockade of the endocannabinoid system. It has been developed from the knowledge that cannabis smokers often experience hunger, which is often referred to as "the munchies". It had been approved in Europe for the treatment of obesity but has not received approval in the United States or Canada due to safety concerns. European Medicines Agency in October 2008 recommended the suspension of the sale of rimonabant as the risk seem to be greater than the benefits.
• Sibutramine (Meridia), which acts in the brain to inhibit deactivation of the neurotransmitters, thereby decreasing appetite was withdrawn from the UK market in January 2010 and United States and Canadian markets in October 2010 due to cardiovascular concerns. In 2010 it was found that sibutramine increases the risk of heart attacks and strokes in people with a history of cardiovascular disease.
• Fenfluramine and dexfenfluramine were withdrawn from the market in 1997, while ephedrine (found in the traditional Chinese herbal medicine má huáng made from the Ephedra sinica) was removed from the market in 2004.
• Lorcaserin used to be approved by the Food and Drug Administration for use in the treatment of obesity before being withdrawn due to cancer risk.
• Recombinant human leptin is very effective in those with obesity due to congenital complete leptin deficiency via decreasing energy intake and possibly increases energy expenditure. This condition is, however, rare and this treatment is not effective for inducing weight loss in the majority of people with obesity. It is being investigated to determine whether or not it helps with weight loss maintenance.
• Though hypothesized that supplementation of vitamin D may be an effective treatment for obesity, studies do not support this. There is also no strong evidence to recommend herbal medicines for weight loss.

Surgery

Main article: Bariatric surgery

Bariatric surgery ("weight loss surgery") is the use of surgical intervention in the treatment of obesity. As every operation may have complications, surgery is only recommended for severely obese people (BMI > 40) who have failed to lose weight following dietary modification and pharmacological treatment. Weight loss surgery relies on various principles: the two most common approaches are reducing the volume of the stomach (e.g. by adjustable gastric banding and vertical banded gastroplasty), which produces an earlier sense of satiation, and reducing the length of bowel that comes into contact with food (e.g. by gastric bypass surgery or endoscopic duodenal-jejunal bypass surgery), which directly reduces absorption. Band surgery is reversible, while bowel shortening operations are not. Some procedures can be performed laparoscopically. Complications from weight loss surgery are frequent.

Surgery for severe obesity is associated with long-term weight loss and decreased overall mortality. One study found a weight loss of between 14% and 25% (depending on the type of procedure performed) at 10 years, and a 29% reduction in all cause mortality when compared to standard weight loss measures. A marked decrease in the risk of diabetes mellitus, cardiovascular disease and cancer has also been found after bariatric surgery. Marked weight loss occurs during the first few months after surgery, and the loss is sustained in the long term. In one study there was an unexplained increase in deaths from accidents and suicide, but this did not outweigh the benefit in terms of disease prevention. When the two main techniques are compared, gastric bypass procedures are found to lead to 30% more weight loss than banding procedures one year after surgery. For obese individuals with non-alcoholic fatty liver disease (NAFLD), bariatric surgery improves or cures the liver.

A preoperative diet such as low-calorie diets or very-low-calorie diet, is usually recommended to reduce liver volume by 16-20%, and preoperative weight loss is the only factor associated with postoperative weight loss. Preoperative weight loss can reduce operative time and hospital stay. although there is insufficient evidence whether preoperative weight loss may be beneficial to reduce long-term morbidity or complications. Weight loss and decreases in liver size may be independent from the amount of calorie restriction.

Ileojejunal bypass, in which the digestive tract is rerouted to bypass the small intestine, was an experimental surgery designed as a remedy for morbid obesity.

The effects of liposuction on obesity are less well determined. Some small studies show benefits while others show none. A treatment involving the placement of an intragastric balloon via gastroscopy has shown promise. One type of balloon led to a weight loss of 5.7 BMI units over 6 months or 14.7kg. Regaining lost weight is common after removal, however, and 4.2% of people were intolerant of the device.

An implantable nerve simulator which improves the feeling of fullness was approved by the FDA in 2015.

In 2016 the FDA approved an aspiration therapy device that siphons food from the stomach to the outside and decreases caloric intake.

Health policy

Obesity is a complex public health and policy problem because of its prevalence, costs, and health effects. As such, managing it requires changes in the wider societal context and effort by communities, local authorities, and governments. Public health efforts seek to understand and correct the environmental factors responsible for the increasing prevalence of obesity in the population. Solutions look at changing the factors that cause excess food energy consumption and inhibit physical activity. Efforts include federally reimbursed meal programs in schools, limiting direct junk food marketing to children, The World Health Organization recommends the taxing of sugary drinks. When constructing urban environments, efforts have been made to increase access to parks and to develop pedestrian routes.

Mass media campaigns seem to have limited effectiveness in changing behaviors that influence obesity. At the same time they can increase knowledge and awareness regarding physical activity and diet, which might lead to changes in the long term. Campaigns might also be able to reduce the amount of time spent sitting or lying down and positively affect the intention to be active physically. Nutritional labelling with energy information on menus might be able to help reducing energy intake while dining in restaurants.

Since there is a relationship between obesity and automobile travel, interventions relating to transportation infrastructure (for example, policy aimed at encouraging the use of public transportation) could potentially reduce obesity.

Clinical protocols

Much of the Western world has created clinical practice guidelines in an attempt to address rising rates of obesity. Australia, Canada, the European Union, and the United States have all published statements since 2004.

In a clinical practice guideline by the American College of Physicians, the following five recommendations are made:

1. People with a BMI of over 30 should be counseled on diet, exercise and other relevant behavioral interventions, and set a realistic goal for weight loss.
2. If these goals are not achieved, pharmacotherapy can be offered. The person needs to be informed of the possibility of side-effects and the unavailability of long-term safety and efficacy data.
3. Drug therapy may consist of sibutramine, orlistat, phentermine, diethylpropion, fluoxetine, and bupropion. Evidence is not sufficient to recommend sertraline, topiramate, or zonisamide.
4. In people with a BMI over 40 who fail to achieve their weight loss goals (with or without medication) and who develop obesity-related complications, referral for bariatric surgery may be indicated. The person needs to be aware of the potential complications.
5. Those requiring bariatric surgery should be referred to high-volume referral centers, as the evidence suggests that surgeons who frequently perform these procedures have fewer complications.

A clinical practice guideline by the US Preventive Services Task Force (USPSTF) concluded that the evidence is insufficient to recommend for or against routine behavioral counseling to promote a healthy diet in unselected people in primary care settings, but that intensive behavioral dietary counseling is recommended in those with hyperlipidemia and other known risk factors for cardiovascular and diet-related chronic disease. Intensive counseling can be delivered by primary care clinicians or by referral to other specialists, such as nutritionists or dietitians. A survey of primary care physicians in the United States found that although clinical guidelines do not consider overweight to be a risk factor that increases mortality, physicians often report believing that being overweight increases all-cause mortality.

Canada developed and published evidence-based practice guidelines in 2006. The guidelines attempt to address the prevention and management of obesity at both the individual and population levels in both children and adults. The European Union published clinical practice guidelines in 2008 in an effort to address the rising rates of obesity in Europe. Australia came out with practice guidelines in 2004.

外部リンク

• Media related to Management of obesity at Wikimedia Commons