Circadian Rhythms And Metabolic Health Essay

In the scientific method lab, I explored the different food options for mice in order to find the best one that will help them gain weight. To succeed in this lab, I needed to examine several types of foods including fruits, raw meat, cooked and uncooked foods. In this experiment I used cooked macaroni as a positive control and for the negative control I didn’t feed the mice any food, only water. The main objective of this study was to determine the best solution that will help me understand the metabolism of mice. All mice used in this study were given the same resources, but the only difference was the different types of foods fed to the mice to understand the changes of weight gain or loss between the mice.

Genetic research of obesity was partly successful in establishing obesity in model organisms – rodents where obesity occurs spontaneously together with other pathological aspects (insulin resistance, …). The main cause of monogenic obesity in these model organisms are common mutations always present in only one gene. Results of research on model organisms allowed us to understand biological mechanisms of calorie intake and regulation and maintenance of body weight. The most important insight into obesity was achieved in 1994 after discovery of ob gene encoding for leptin. In two years period, using screening method, candidate homologous genes, selected on genetic study basis on mice, another five genes were identified. Mutations on these genes were found to be the cause of autosomal recessive or dominant monogenic obesity. Products of these genes are leptin and its receptor, proopiomelanocortin (POMC) melanocortin receptor 4 (MC4R) and

In wild type mouse there is no effect on food intake, body weight and blood glucose though we give more leptin because here the leptin receptors are constant. But, in ob/ob mouse the food intake, body weight and blood glucose levels are decrease because the presence of leptin receptor. However, in the db/db mouse there is no effect due to the absence of the leptin

The RER of both TRF groups was significantly higher during the feeding phase and significantly reduced during the fasting phase than their ad-lib counterparts. Using 45 mice, Chung and colleagues12 studied an 8-hour high-fat TRF diet over 27 weeks. RER was measured from 6 p.m. to 10 p.m., 10 p.m. to 6 a.m. (TRF period), and 6 a.m. to 6 p.m. RER for the ad-lib group was approximately 0.75 throughout the study. RER for the TRF group was 0.70 from 6 a.m. to 10 p.m. and increased during the TRF period. Comparing the two groups, the RER of the TRF group was significantly lower than the ad-lib group from 6 p.m. to 10 p.m., significantly higher than the ad-lib group during the TRF period, and similar to the ad-lib group from 6 a.m. to 6 p.m. In Moro et al.’s18 8-hour TRF study with 34 men, RER was measured between 6 a.m. and 8 a.m. At the end of the study, the RER decreased significantly in the TRF group compared to baseline (0.83 ± 0.02 to 0.81 ± 0.01). Yet the RER in the TRF group was the same as the ad-lib group (0.83 ± 0.02). Sundaram and Yan13 tested the impact of an 8- and 12-hour high fat TRF diet on RER in mice. The diurnal rhythms of RER oscillations of the TRF groups (ranging from about 0.9 to 0.75 between the feeding and fasting cycles) were improved compared to the high-fat ad-lib mice.

Fat storage was measured on the rats between the two different diet groups in order to observe where fat may be prevalent within the different diets. The rat on the lean diet did not gain weight as quickly as the rat on the higher fat westernized det. During the first weight measurement, the rat on the higher fat diet is about twice the size of the rat on the leaner diet and although both rats are gaining weight the rat on the westernized diet is gaining weight substantially quicker (Figure). The liver weight between the two different diet groups was shown to not have a big difference as the higher fat rat liver weight was only slightly higher than the leaner rat (figure). When looking at the omental fat storage there is a bigger difference.

In this study 16 obese subjects were put on an alternate-day fast to help facilitate weight loss and lower cardiovascular disease (CAD) risk. After as 10-week trial period the ADF diet helped obese individuals not only lose weight, but also decrease CAD risk. In addition to this, a similar experiment was conducted in mice, where they had obese mice on alternative day fasting regimen. These obese mice lost weight and had an improvement in their glucose tolerance (Joslin et al., 2016).

The expression of leptin by adipose tissue is also influenced by feeding behaviour. Short-term (12 h) or long-term (2 or 8 weeks) overfeeding results in an increase in adipocyte leptin expression and circulating leptin in healthy human subjects. Furthermore, circulating leptin levels show a diurnal pattern and are influenced by gender, age, exercise and glucose uptake (Table 3).

Leptin, which is a peptidic hormone (possessing two or more amino acids), essentially serves as a messenger between the brain and fat tissue, and has been noted to aid in the maintenance of body weight. In many animal models, which include rats and mice, obesity was found to be caused by mutations in the rodents' leptin and leptin receptors, where single mutations (mutations where changes occur to only one nucleotide base) occurred in the coding area or the 5' end of the non-coding region of the leptin gene. This sparked the interests of many scientists, as they began to wonder if mutations in leptin and its receptors may also be responsible for obesity in humans. At first, no evidence was found of this being true, but recently, new research suggests that particular forms of obesity in humans may be the result of mutations of the leptin gene. Early experiments of parabiosis had been done with mice, where two individuals were joined anatomically, and recognized that the lack of leptin was responsible for them having the complex, obese phenotype. Although the ob/ob mice could be treated with leptin, the db/db mice were not affected by the treatment of leptin, having researchers come to the conclusion that the incapability to respond to leptin is the cause of mutations in the leptin receptors.

Resting metabolic rate (RMR) as main part of daily energy expenditure (14) has principal role in energy balance. Indeed, resting metabolic rate can effect on adiposity or weight gain(14, 15). Our results demonstrated that RMR/kg had reverse significant correlation with weight, BMI and visceral fat. Some pathogenetic explanation for lower energy expenditure in obese subjects with metabolic syndrome may be the lipotoxic theory, lower levels of uncoupling proteins in mitochondria and genetic polymorphism in them(17)

Meal pattern Analysis represents an analytical examination of the distribution of the drinking and feeding episodes over the light-dark cycle and was shown to be altered in several animal models of obesity (Clifton 200, Moran 2003, Cottone et al. 2007). A meal is generally defined by the association of the different intake bouts separated by less than a determined inter-meal interval. Meal pattern analysis provides information about meal number, meal duration, meal size, intermeal interval, eating rate and satiety ratio (Le Magnen and Devos 1980, Moran 2003, Zorilla et al. 2005). The study of feeding pattern is now considered as an indispensable parameter to be evaluated for understanding the principles governing ingesting behaviour and his lost of control (Geary, 2005). At present, if the equipment and tools available for the study of drug consumption

The non-genetic causes of obesity in all over the world are increase in uptake of high caloric junk food, increase in inactive lifestyle, increase in luxurious travelling [5]. Obesity seems to emerge as a major health epidemic due to the sedentary so called modern lifestyle [2]. The change in our behaviors toward food and physical activities has resulted in the shape of high obesity levels world-wide. When high caloric food is consumed, excessive amount of energy is stored in the form of fats in adipose tissue. The use of energy is in the form of basal metabolic rate, including the thermic effect of food and physical activity (both exercise and non-exercise movements). With the passage of time, if the lifestyle remains sedentary along with

In an attempt to find out how extensive the effects of breakfast skipping on obesity, a study was

Furthermore, irregular meal time could cause illnesses of insulin resistance and diabetes. Human body actually tries to memorise consumption pattern so that to control the secretion of chemicals in digestive system such as insulin. Irregular consumption makes body sugar rate variable since digestion could not be achieved effectively. Unstable blood sugar concentration would lead to risk of diabetes.

My target area began as a focus on eating more in general. The food available at PSP was not always ideal, many times the food was either unhealthy or there simply weren’t enough options that I enjoyed. As a result, I noticed that my weight began to significantly decline and I desperately wanted to allay this problem. After completing my log sheets over three weeks, I came to the realization that the bulk of my missed meals came in the morning. I would sleep until eight to make sure that I received adequate sleep, however, I realized that in doing this; I was forgoing breakfast which was negatively affecting my health and my performance at Cornell. In fact, “research involving adults and children has indicated that breakfast might enhance memory, attention, the speed of processing information, reasoning, creativity, learning, and verbal abilities” (Consumer Reports). No matter a person’s age, breakfast is a vital part of their life.

As a night owl, staying up late can create bad eating habits. Cutting back on sleep increases the likelihood of indulging high calorie foods which may eventually lead to obesity. As the lead study author at the University of Pennsylvania, Andrea M. Spaeth tested a group of 27 participants who went to bed at 10 pm and another group of 198 who went to bed at 4 am. Their results concluded that the second group had consumed significantly more food than the first group. As Spaeth stated, the longer we stay awake, the more time we get to eat high fat foods.