Obesity is a condition that is associated with excessive levels of body fat, obesity is considered a major health problem in Western Countries. Between 2014 and 2015 a staggering 63.4% of the population was overweight. This is an increase of 19% from 1995. In the same period, there was about 22,700 hospital separation involving one or more weight loss procedure, seven of eight of these procedures happened in private hospitals. 79% of these where for female patients. Figures also indicate that from 2005-2006 to 2014-25 weight loss surgeries more than doubled from about 9,300 to 22,700 (Gupta et al., 2016).
In Australia and other industrialised countries, there is a growing concern for the rising levels of childhood obesity. Recent figures indicate that 28% of children and adolescents are considered as overweight or obese. In certain groups of people such as Aboriginal and Torres Islands figures appear to be even higher. In children being overweight can leave some short and long-term impacts, for example, low self-esteem and depression, body image issues and increased risk of developing eating disorders to name a few (Sainsbury, Hendy, Magnusson, & Colagiuri, 2018).
The World Health Organisation has classified obesity as a global epidemic, Overweight or obese people have higher rates of cardiovascular diseases, diabetes mellitus and cancer, other problems that are associated with obesity include, gastro-oesophageal reflux disease, sleep disorders and chronic joint pain. In some countries, the morbidity and mortality for obese people are second only to smoking cigarettes. The causes of obesity are complex and involve a combination of genetics, physiological and lifestyle factors.
An Individual’s body mass is a product of their total energy intake and expenditure. A person is said to be in energy balance when the food intake equals the energy that is consumed by the body cells. When this occurs in adults the individual will neither gain weight or lose weight, this also assumes the daily fluid intake and out stays the same.
Daily changes in the total energy intake and expenditure do happen, but as long as the individual manages to maintain this energy balance the total body weight will be maintained. The rate of energy expenditure determines the rate of usage by the body, it can be measured as oxygen consumption and body temperature. Factors that increase metabolism include physical activity, sympathetic nervous system stimulation and raised body temperature (Dhurandhar et al., 2015).
Regulation of Food Intake
In humans there are two feeding centres which are both located in the hypothalamus, one is associated with hunger and stimulates eating. The other is associated with the sense of fullness and inhibits eating. The hunger centre is always active, but it is intermittently inhibited by the satiety centre. These centres respond to the noradrenaline signals, paracrine signals, blood nutrient levels and psychosocial factors. Stimuli that can trigger eating are numerous, for example, particular tests and smell, low blood sugar levels, some drugs such as marijuana and low ambient temperatures (Houben, Dassen, & Jansen, 2016).
Another essential substance that regulates hunger is a hormone that is secreted by the stomach called Ghrelin. The blood of this substance fluctuates during the day but are quite elevated prior to a meal and the decrease afterwards. Obese individuals tend to have lower levels of Ghrelin, whereas people with anorexia tend to have higher levels. What is interesting is that the speed to which Ghrelin drops can be influenced by the type of foods that are consumed.
Recent studies show that Ghrelin regulates glucose balance by inhibiting insulin secretion and regulating gluconeogenesis. Another thing Ghrelin signalling does is that it reduces thermogenesis so as to regulate energy expenditure. Perhaps what is even more interesting about this hormone is that it improves the survival prognosis of heart attacks by reducing sympathetic nerve activity (Pradhan, Samson, & Sun, 2013).
On the other hand, there is a number of chemical mediators that suppress appetite and reduce food intake. The monoamine neurotransmitter noradrenaline and serotonin tend to inhibit eating. Another hormone (CCK) that is secreted in response to triglycerides in the gastrointestinal tract. It rapidly stimulates the satiety centres of the hypothalamus to stop eating. Some researchers have indicated that eating disorder like Bulimia may be associated with impaired CCK secretion (Al Shukor, Raes, Van Camp, & Smagghe, 2015).
Role of Leptin
Leptin is a hormone that is released from the fat cells located in the adipose tissue, leptin helps regulate and alter long-term food intake and expenditure, not just from meal to meal. The primary design for leptin is to help the body maintain weight. Because leptin comes from the fat cells, the levels of leptin an individual is directly connected to the fat composition of the body. If the individual ads fat the levels of leptin increase. Leptin helps inhibit hunger and regulate energy balance so that the body does not trigger the hunger responses when the body needs energy. When the levels of leptin fall, as is the case in people who lose weight, it can trigger increase in huge appetite and food cravings.
In normal circumstances when the body is functioning well, excess fat cells will produce leptin which will trigger the hypothalamus to lower the appetite. This allows the body to deep into the fat stores to feed itself. In obese individuals, they have too much leptin in the blood. This can cause leptin resistance, where the body is no longer sensitive to the hormone. Low levels of leptin do happen, but this is rare, this is called congenital leptin deficiency. In Congenital leptin deficiency, the body does not produce leptin. And without leptin, the body thinks it has fat and this causes intense uncontrollable hunger and food intake. Congenital leptin deficiency often manifests in severe childhood obesity and delayed puberty (Park & Ahima, 2015).
The internet is saturated with countless weight loss and super diet programs, each one of them promising faster weight loss results. But by far the best way to lose weight is by setting a sustainable and realistic program involving diet and exercise. Foods that should be avoided within reason and depending on your lifestyle are simple carbohydrates, processed sugars and processed meats. According to dietitians, sudden spurts of exercises use carbohydrate stores, whereas steady exercises uses fat stores.
Suggestion for safe and effective weight loss
- Do not crash diet, you will most likely regain the lost weight
- Aim for small slow loses of around 1Kg per week
- Cut down on dietary fats especially saturated fats and increase the general intake of fruits and vegetables.
- Exercise at least three days a week, or generally increase your overall physical activity.