The most basic function of bodily fat is self-storage of food reserves. In prehistoric times, natural selection favored genotypes that could endure harsh conditions by stocking the most fat. With chronic malnutrition being the norm for most of human history, genetics evolved to favor fat storage. So when did body fat become problematic? The negative impacts of being overweight were not even noted in medical literature until as late as the 18th century. Then, technological advances coupled with public health measures resulted in the betterment of the quantity, quality, and variety of food. Sustained abundance of good food enabled a healthier population to boom economically. Output increased, and with it, leisure time and waistlines. By the mid 19th century, being excessively overweight, or obese, was recognized as a cause of ill health, and another century later, declared deadly. What is the distinction between being overweight and being obese? A calculation called the BMI breaks it down for us. For example, if someone weighs 65 kilgorams and is 1.5 meters tall, they have a BMI of about 29. Obesity is a condition of excess body fat that occurs when a person's BMI is above 30, just over the overweight range of 25 to 29.9. While BMI can be a helpful estimate of healthy weight, actual body fat percentage can only really be determined by also considering information like waist circumference and muscle mass. Athletes, for instance, have a naturally higher BMI. So how does a person become obese? At its most basic, obesity is caused by energy imbalance. If the energy input from calories is greater than the energy output from physical activity, the body stores the extra calories as fat. In most cases, this imbalance comes from a combination of circumstances and choices. Adults should be getting at least 2.5 hours of exercise each week, and children a whole hour per day. But globally, one in four adults and eight out of ten adolescents aren't active enough. Calorie-dense processed foods and growing portion sizes coupled with pervasive marketing lead to passive overeating. And scarce resources, and a lack of access to healthy, affordable foods creates an even greater risk in disadvantaged communities. Yet, our genetic makeup also plays a part. Studies on families and on separated twins have shown a clear causal hereditary relationship to weight gain. Recent studies have also found a link between obesity and variations in the bacteria species that live in our digestive systems. No matter the cause, obesity is an escalating global epidemic. It substantially raises the probability of diseases, like diabetes, heart disease, stroke, high blood pressure, and cancer. It affects virtually all ages, genders, and socioeconomic groups in both developed and developing countries. With a 60% rise in child obesity globally over just two decades, the problem is too significant to ignore. Once a person is obese, the climb to recovery becomes progressively steeper. Hormonal and metabolic changes reduce the body's response to overeating. After losing weight, a formerly overweight person burns less calories doing the same exercises as a person who is naturally the same weight, making it much more difficult to shed the excess fat. And as people gain weight, damage to signaling pathways makes it increasingly difficult for the brain to measure food intake and fat storage. There is, however, some evidence that well-monitored, long-term changes in behavior can lead to improvements in obesity-related health issues. And weight loss from sustained lifestyle changes, or invasive treatments like bariatric surgery, can improve insulin resistance and decrease inflammation. What was once an advantage for survival is now working against us. As the world's population continues to slow down and get bigger, moving and consciously eating our way towards a healthier weight is essential to our overall well-being. And with the epidemic affecting every country in the world for different socioeconomic reasons, obesity cannot be seen as an isolated issue. More global measures for prevention are essential to manage the weight of the world.
Osnovna funkcija telesne masti je skladištenje rezervi hrane. U praistorijska vremena, prirodnom selekcijom birani su genotipi koji bi mogli da prežive teške uslove tako što skladište najviše masti. Kako je većim delom ljudske istorije hronična neuhranjenost bila standard, razvili su se geni koji favorizuju skladištenje masti. Kada su telesne masti postale problematične? Negativni uticaji preterane težine nisu primećeni u medicinskoj literaturi sve do 18. veka. Tadašnji razvoj tehnologije zajedno sa merama javnog zdravstva za posledicu imao je poboljšanje količine, kvaliteta i raznovrsnosti hrane. Održivo obilje dobre hrane omogućilo je da zdravije stanovništvo ekonomski procveta. Povećao se učinak, a samim tim i količina slobodnog vremena i obim strukova. Do sredine 19. veka, višak kilograma ili gojaznost, bio je prepoznat kao uzrok pogoršanog zdravlja, a jedan vek kasnije, proglašen je i smrtonosnim. Koja je razlika između viška kilograma i gojaznosti? To nam pokazuje jednačina zvana ITM, indeks telesne mase. Na primer, ako neko ima 65 kilograma a visok je 150cm, znači da mu je ITM oko 29. Gojaznost je stanje viška telesne masti koje se javlja kada je ITM kod neke osobe iznad 30, tik iznad granice viška kilograma, od 25 do 29,9. Dok ITM može biti koristan da se odredi zdrava težina, pravi procenat telesne masti zapravo se jedino može utvrditi kad se uzmu u obzir informacije poput obima struka i mase mišića. Na primer, sportisti prirodno imaju više vrednosti ITM. Kako neko postane gojazan? U samoj osnovi, do gojaznosti dolazi kroz energetsku neravnotežu. Ukoliko je unos kalorija veći od energije koja se proizvede fizičkom aktivnošću, telo skladišti višak kalorija kao mast. Do ove neravnoteže uglavnom dolazi kroz kombinaciju faktora i izbora. Odrasle osobe bi trebalo da vežbaju najmanje 2,5 sata nedeljno, a deca jedan sat dnevno. Ali na svetskom nivou, svaka četvrta odrasla osoba i 8 od 10 adolescenata nije dovoljno aktivno. Prerađena hrana bogata kalorijama kao i porcije koje rastu zajedno sa ubedljivim reklamama dovode do pasivnog prejedanja. Manjak resursa, kao i nedostatak pristupa zdravoj, pristupačnoj hrani stvaraju još veći rizik u nerazvijenim zajednicama. Ipak, ulogu igra i naša genetika. Istraživanja na porodicama i razdvojenim blizancima pokazala su jasnu posledičnu naslednu povezanost sa gojenjem. Skorašnja istraživanja takođe su pokazala vezu između gojaznosti i varijacija u vrstama bakterija koje žive u našim sistemima za varenje. Bez obzira na uzrok, gojaznost je globalna epidemija u porastu. Ona značajno povećava verovatnoću raznih bolesti, poput dijabetesa, srčanih bolesti, moždanog udara, visokog krvnog pritiska i raka. Ona pogađa bez obzira na godište, rod i socioekonomsku grupu, u razvijenim i nerazvijenim zemljama. Sa porastom od 60% u dečjoj gojaznosti širom sveta tokom samo dve decenije, problem je previše značajan da bi se ignorisao. Kada osoba jednom postane gojazna, put do oporavka postaje znatno teži. Promene u hormonima i metabolizmu značajno smanjuju reakcije tela na prejedanje. Nakon gubitka težine, prethodno gojazna osoba sagoreva manje kalorija radeći iste vežbe kao osoba koja prirodno ima istu težinu, zbog čega je mnogo teže rešiti se viška sala. A kako se ljudi goje, šteta naneta kanalima za komunikaciju mozgu značajno otežava da meri unos hrane i skladištenje sala. Ipak, postoje dokazi da pravilno praćene dugotrajne promene u ponašanju mogu da dovedu do poboljšanja kod bolesti povezanih sa gojaznošću. A gubitak kilograma koji nastaje kroz održive promene životnog stila ili invazivne poduhvate poput barijatrijske operacije, može da poboljša insulinsku otpornost i smanji upale. Ono što je bilo prednost za preživljavanje sada radi protiv nas. Kako svetska populacija nastavlja da se usporava i goji, kretanje i svesna ishrana ka zdravijoj telesnoj težini ključni su za našu dobrobit. Kako epidemija pogađa svaku zemlju na svetu, iz raznih društveno-ekonomskih razloga, gojaznost se ne može posmatrati kao izolovan problem. Postojanje više globalnih mera prevencije je ključno da bi se kontrolisala težina ovog sveta.