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.
Tanadagi yog’ning asosiy vazifasi oziq-ovqat zaxiralarini saqlashdir. Qadimgi davrlarda yuqori yog' zaxiralari hisobiga og'ir sharoitlarga bardosh bera oluvchi genotiplar tabiiy tanlanish jarayonida omon qolgan. Surunkali to'yib ovqatlanmaslik insoniyat tarixida odatiy hol bo'lganligi sababli asta-sekin tanada yog' yig'ishga moyillik paydo bo'lgan. Qachondan beri tanadagi yog' zaxirasi muammoga aylandi? XVIII asrga qadar semizlikning salbiy oqibatlari haqida tibbiy adabiyotlarda hech qanday ma'lumot uchramaydi. Keyinchalik, texnologiya taraqqiyoti va sog'liqni saqlash chora-tadbirlari tufayli oziq-ovqat sifati, miqdori va uning xilma-xilligi yaxshilandi. Sifatli oziq-ovqatning mo'l-ko'lligi sog'lom aholining iqtisodiy rivojlanishiga imkon berdi. Ishlab chiqarish samaradorligi va bu bilan birga bo'sh vaqt miqdori hamda bel aylanasi o’lchami ham oshdi. XIX asrning o'rtalariga kelib, ortiqcha vazn yoki semizlik sog'liq yomonlashganiga sabab sifatida ko'rsatila boshlandi. Bir asr o'tgach esa uning o'limga olib kelishi mumkinligi aniqlandi. Ortiqcha vazn va semizlik o'rtasidagi farq nimada? TVI – tana vazni indeksi orqali bunga javob topish mumkin. Masalan, agar kishi vazni 65 kg, bo'yi 1,5 metr bo'lsa, TVI taxminan 29 ni tashkil etadi. Semizlik tanadagi ortiqcha yog'larning mavjudligi bo'lib, bu odamda TVI darajasi 30 dan oshganda yuzaga keladi. Ortiqcha vazn esa odatda 25-29,9 atrofida bo'ladi. TVI sog'lom vaznni aniqlash uchun foydali ko'rsatkich bo'lsa-da, yog'ning haqiqiy foizini faqat bel aylanasi va mushak massasini hisobga olgan holda aniqlash mumkin. Masalan, sportchilarda TVI darajasi doim yuqori bo'ladi. Xo'sh, odam qanday qilib semiradi? Semizlik ko'pincha energiya nomutanosibligidan kelib chiqadi. Agar kaloriyadan hosil bo'lgan energiya miqdori jismoniy faoliyatga sarflangan energiya miqdoridan ko'p bo'lsa, organizm ortiqcha kaloriyani yog' shaklida saqlay boshlaydi. Ko'p hollarda bu nomutanosiblik turli shart-sharoit va inson tanlovi natijasida yuzaga keladi. Kattalar jismoniy mashg'ulotlarga haftasiga kamida 2,5 soat, bolalar esa kuniga bir soatdan vaqt ajratishlari kerak. Ammo dunyo bo'ylab har to'rt kishidan bittasi va har o'nta boladan sakkiztasi jismonan nofaol. Kaloriyaga boy tayyor ovqatlar, ular hajmining ko'payishi hamda keng yoyilgan marketing nofaol turmush tarzi va ko’p ovqatlanishga olib keladi. Resurslarning yetishmasligi, sifatli va arzon oziq-ovqat tanqisligi jamiyatning nochor qatlami uchun yanada katta xavf tug'diradi. Ammo bizning genetik tuzilishimiz ham muhim rol o’ynaydi. Oilalar va ajratilgan egizaklar bilan olib borilgan izlanishlar irsiyat va vazn ortishi o'rtasidagi bog'liqlikni aniqladi. So'nggi yillarda o'tkazilgan tadqiqotlar ham semizlik va hazm qilish tizimining bakterial tarkibidagi farqlar o'rtasidagi aloqani aniqladi. Muammo sabablaridan qat'iy nazar, semizlik global epidemiyaga aylandi. U diabet, yurak kasalligi, insult, yuqori qon bosimi va saraton kabi kasalliklarning paydo bo'lish ehtimolini sezilarli darajada oshiradi. U rivojlangan va rivojlanayotgan mamlakatlarda jinsi, yoshi va ijtimoiy kelib chiqishidan qat'i nazar, barchaga ta'sir qilishi mumkin. So'nggi 20 yil ichida dunyo bo'ylab bolalarda semizlik darajasi 60 %ga oshdi, shu bois bu o'tkir muammoni e'tiborsiz qoldirib bo'lmaydi. Kishi semirar ekan, uning vazn yo'qotishi yanada qiyinlashadi. Gormonal va metabolik o'zgarish sabab tana ko’p ovqatlanishga qarshilik qilolmaydi. Semiz odam vazn yo'qotgach, vazni o'zgarmagan odam bilan bir xil mashq bajarsa-da, ozroq miqdorda kaloriya sarflaydi, bu esa ortiqcha yog'dan qutulishni qiyinlashtiradi. Vazn ortishi signal yuborish yo'llarini shikastlab, ma'lumot uzatishga xalaqit beradi, miyaning iste'mol qilingan oziq-ovqat miqdori va yog' zaxirasini o'lchashi qiyinlashadi. Inson uzoq vaqt davomida o'z xatti-harakatlarini qat'iy o'zgartirsa, semizlik bilan bog'liq muammoni bartaraf etishi mumkinligi haqida ayrim dalillar mavjud. Turmush tarzining doimiy o'zgarishi yoki bariatrik jarrohlik orqali vazn yo'qotish insulin faoliyatini yaxshilaydi va yallig'lanishni kamaytiradi. Bir paytlar omon qolish uchun bizga ustunlik bergan narsa hozir o'zimizga qarshi ishlamoqda. Dunyo aholisi kamharakat bo'lib, vazni ortib borar ekan, faol harakat va oziq-ovqatga xushyorlik tana salomatligi uchun zarur bo'lgan sog'lom vazn kalitidir. Epidemiya turli xil ijtimoiy-iqtisodiy sabablarga ko'ra barcha dunyo mamlakatlarida tarqalayotgan ekan, semizlik muammosini yolg'iz hal etib bo'lmaydi. Sayyoramiz aholisi vaznini yaxshilash uchun dunyo bo'ylab zarur chora-tadbirlarni kuchaytirish zarur.