Obesogenic factors and environments contributing to rising rates of obesity in Mexican children
Mexico has one of the highest youth obesity rates worldwide currently at 34% of all children and adolescents. This problem is rapidly worsening in Mexico with drastic consequences. There is limited understanding of the factors driving the rapidly increasing rates in Mexico. An understanding of determinants is critical to developing interventions, health programs and policies to effectively take on the crisis.
A recent review in Global Health Action set out to compile, describe, and analyse dietary conditions, physical activity, socioeconomic status, and cultural factors that create and exacerbate an obesogenic environment among Mexican youth. The authors approached this through a narrative review conducted across scientific databases and governmental reports.
The findings revealed a multitude of contributing factors including reduced healthy meal options at public schools, high rates of sedentary lifestyles among adolescents, lack of open spaces and playgrounds, socioeconomic deprivation, false or misunderstood sociocultural traditional beliefs, misconceptions about health, a high percentage of overweight or obese adults, and low rates of maternal breastfeeding. The factors identified are exacerbating the obesity problem in this population. From this evidence it is apparent that the average Mexican child is surrounded by a multitude of obesogenic factors driving rising rates of obesity. Measures to control these factors is drastically needed to stop continuation of the escalating rates.
Read MoreAcute and Chronic Effects of Exercise on Appetite, Energy Intake, and Appetite-Related Hormones
The simple equation for obesity is Energy out < Energy in. The simplest way of increasing our ‘Energy out’, is to exercise more. However, the benefits of exercise extend beyond just calories, and in fact, it’s thought that exercise can improve subjective and homeostatic mediators of appetite in directions associated with enhanced meal-induced satiety. The degree to which this effect exists in an individual is highly variable and difficult to predict. This review, published in Nutrients, seeks to understand how adiposity, sex, and habitual physical activity modulate exercise-induced appetite, energy intake, and appetite-related hormone responses.
The review found that changes in perceptions of appetite, energy intake, and macronutrient composition in response to acute and chronic exercise stimuli are not modulated by levels of body adiposity or sex. However, in individuals with higher levels of habitual physical activity, they may exhibit improved sensitivity of the appetite control system through better compensatory adjustments for the energy content and density of food.
Although not conclusive, this paper draws attention to the benefits of exercise and need for an improved understanding of the individual factors that modulate appetite, appetite-related hormones, and food intake. Responses to exercise may help to explain the individual variability in body weight changes, and to facilitate the development of more efficacious weight management interventions.
Read MoreA long-term maternal diet intervention to avoid the obesogenic effect in the offspring
The American Heart Association states that obesity among girls and women has generated a vicious cycle that contributes to the obesity epidemic. Studies into maternal overnutrition have found that high-fat diets in humans (which reflects the western diet), whereby the baby is exposed to over-nutrition during gestation, have increased risks of obesity, diabetes and other complications. In this study, published in The Journal of Nutritional Biochemistry, the diets of pregnant mice are varied to see whether they can prevent obesity related disease in the offspring, regardless of the weight-management of the mother.
The researchers transitioned the mice to normal fat (NF) diet 1 week, 5 weeks and 9 weeks before conception and continued this throughout gestation and lactation. After this, the offspring were given a high-fat diet for 12 weeks then sacrificed. They found that the mice whose parent had the NF diet for 9 weeks had a reduced risk of obesity, diabetes and other complications, regardless of maternal weight, suggesting a metabolic memory in the offspring that can be improved. Although the metabolic profiles of mice and humans are vastly different, the ease of access and economy of lifestyle interventions mean that a strategy to improve maternal diet for a period before conception, may be able to help prevent multi-generational obesity.
Read MoreEating faster is associated with general and abdominal obesity among Chinese children
Eating faster results in an increased rate of energy intake. However, the relationship between children’s eating speed, food intake and general abdominal adiposity is unknown, and forms the basis of this paper. A total of 50,037 Chinese children aged 7-17 years were enrolled from 7 provinces in China in 2013. Objective measurements of anthropometrics were taken and food speed was assessed by questionnaire.
There was a significant increasing trend across the slow, medium, and fast eating speed groups observed, in the prevalence of general obesity (7.2%, 10.0% and 15.9%), abdominal obesity (16.1%, 21.8%, and 29.4%) and waist-to-height ratio (WHtR) ≥ 0.5 (11.1%, 14.8%, and 22.0%). Compared with medium eating speed, fast eating speed was positively associated with obesity, abdominal obesity, and WHtR ≥ 0.5, while slow eating speed was negatively associated with these outcomes. They also found increased speed was associated with increased consumption.
Although this paper doesn’t tell us anything of the mechanism of this phenomenon, there are several biologically plausible suggestions. Such as, fast-eating leads to lower satiety and higher calorie intake, while slow-eating leads to enhanced thermic effect of food and also influences the release of gastrointestinal satiety hormones. More research should be done to see if it’s possible to change eating speed in adults, and whether this has any effect on obesity, as this could provide a simple non-invasive therapeutic target.
Read MoreImpact of overweight, obesity and severe obesity on life expectancy of Australian adults
Obesity is known to significantly elevate the risk of many health problems, however its impact on life expectancy (LE) has not been quantified in Australia. This paper, published in the International Journal of Obesity, uses a microsimulation model of obesity progression to predict the changes in LE and years of life lost (YLL). It uses data on annual change in BMI based on age and sex, with Australian life-table data and published relative risk of all cause-mortality for different BMI categories. A nationally representative sample of 12,091 adults aged 20-69 were used.
The study predicted that the loss in LE for obese people to be 5.6-7.6 years and for severely obese people to be 8.1-10.3 years for men and women aged 20-29 years. If the baseline BMI was higher, so at age 20-29 BMI was above 25, years lost was greater. It also found that men lost 27.7% more years compared to women. In total, overweight and obesity was predicted to be responsible for 36.3 million YLL over the life course, with the severely obese contributing almost one-third of the life years lost despite comprising only 11% of the population.
This study does not take into account the impact that increased BMI has on quality-of-life, however evidence has shown there are significant impairments to health related quality-of-life for individuals at more severe levels of obesity as a result of co-morbidity and disability. This paper highlights the huge burden of disease in Australia, particularly in men, that needs to be addressed. The implication on the economy and the individual of 36.3 million YLL are too huge to ignore.
Read MoreAnalysis of the impact of rising food prices on obesity in women across 31 low and middle-income countries
In this longitudinal study, published in the International Journal of Obesity, the authors examine whether changes in food prices are associated with changes in obesity prevalence among women in developing countries, and assess the effect of individual socioeconomic status (SES). Anthropometric data, including BMI, and country-level food price inflation from low and middle income countries (LMIC) was used from 296,000 non-pregnant adult women, over the period 2000 to 2014.
The researchers found a strong link between food price inflation and obesity in adult women in LMICs, and the relationship is consistently modified by individual SES. Regardless of indicator used, higher food price inflation was positively associated with obesity among women in top SES categories, but was flat or negative among women in low SES categories, averaging over time. In lower SES groups it’s hypothesized that this is a result of a relative lack of exposure to food pricing, due to them growing their own food. Educational differences appeared the strongest of all SES measures which is consistent with the literature on social determinants of obesity.
This response to food budget constraints is recognised by other comparisons of LMICs, showing that individuals greatly reduce fruit and vegetable intakes as the relative cost increases [2], and that only those in the highest socioeconomic groups increase caloric intake in response to rising food prices. As the international burden of obesity grows, it’s important to understand how economic fluctuations translate into behavioural changes
Read MoreEfficacy and safety of semaglutide for weight loss in patients with obesity
In this paper, published in The Lancet, the authors sought to assess efficacy and safety of the glucagon-like peptide-1 (GLP-1) analogue semaglutide, in comparison with a similar drug liraglutide, and placebo. The study was done in 8 countries, involving 71 clinical sites, with the primary endpoint being weight loss at week 52.
GLP-1 analogues mimic the function of human GLP-1, which regulates insulin secretion and glucagon secretion. These processes are linked with appetite, satiety and energy intake. This study found that these drugs, which were initially licensed for diabetes treatment, resulted in weight reductions which were significantly greater than the placebo group at 52 weeks. This weight loss is primarily due to the individuals consuming less energy, because of a combination of appetite suppression and enhanced satiety. Semaglutide was found to be the most effective, with weight loss of 11-14%, compared to Liraglutide’s 7-8%. In terms of side-effects, the most common complaint was of nausea. This was found to be dose dependent, so higher doses made side-effects more likely. Overall however, semaglutide was well tolerated, with no unanticipated safety or tolerability outcomes. Semaglutide has been shown to have a good benefit-risk profile which further supports its use as a weight management drug in its own right, instead of just being licensed for diabetes. Phase-3 studies are ongoing.
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Selective enzyme inhibitor reveals a novel role in fat metabolism
Cellular metabolism is a chain reaction of steps, controlled and aided by enzymes, which leads to the production of molecules that the cell requires. An important family of metabolites, called ceramides, are known to have an important role in cell signalling and apoptosis, as well as other physiological functions
In this study published in Nature, the researchers tested a new selective enzyme inhibitor called CerS1 on mice being fed a variety of different diets. They discovered that it has an important role in fat metabolism, specifically on fat deposition in mice. When they used the enzyme to inhibit metabolism, they significantly lowered fat deposition in mice, even if they were on a high-fat diet. They also found that it did not impact on glucose disposal nor insulin stimulated glucose uptake.
Although a lot more research is needed to go from mice studies to human trials, by directly affecting the cellular metabolism to prevent fat deposition, this research has demonstrated a potentially exciting new therapeutic avenue for treating obesity.
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Does environment influence childhood BMI? A study of children aged 3–11
Obesity is simply caused by an imbalance in energy consumed and calories burned, however what causes this imbalance is complex and multifactorial. If enough calories are burned through physical activity, then an individual should not gain weight. Following this rationale, if an environment is more conducive to exercise then an individual is less likely to be overweight. This argument is the basis of this paper, which explores the relationship between environment and children’s BMI.
The study included 6001 children in England, between the ages of 3 and 11. The environmental measures used looked at levels of green space, gardens, crime or multiple deprivation of a neighbourhood. Crime rates were derived from police force data, on four criminal offences; burglary, theft, criminal damage and violence. The study found that there was a moderate relationship between environment and a child’s BMI, however it is unlikely that this relationship was causal. The results instead suggest that environmental variables, such as amount of parks or recreational facilities, may be driven by selection. So those families that are less likely to have overweight children, are more likely to choose to live in greener areas. This research goes against many previous studies which suggests a strong causal link between exercise promoting environments and obesity. In light of this, future research and health policy should consider the assumption that these two are linked and that managing the environment will invariably lead to lower levels of obesity.
Read MoreCardiovascular Safety of Lorcaserin in Overweight or Obese Patients
In some patients, weight-loss guidelines recommend the use of pharmacological agents as adjuncts to lifestyle modification. Although not many are licensed, they have been shown to be effective for long-term weight management. One of the serious downsides of these drugs is the side-effects. Depending on their sight of action, they have been known to precipitate severe complications in the cardiovascular or neuropsychiatric systems, leading to their removal by regulatory agencies over safety concerns.
Lorcaserin is a selective serotonin 2c receptor agonist that modulates appetite. It has proven efficacy for weight management in overweight or obese patients. This paper published in the New England Journal of Medicine sought to determine the cardiovascular risk associated with its use as an obesity treatment. From the study of 12,000 patients, it found no increased risk of cardiovascular complications. It also found that alongside significant weight loss there were also reductions in triglyceride levels and in dysglycaemia. In addition, it was found that there was an improvement in heart rate and blood pressure, which is in contrast to most other weight loss agents. Overall, this drug is an effective adjunct to lifestyle interventions in patients with obesity and cardiovascular disease, and doesn’t increase the risk of cardiovascular events.
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Obesity and loss of disease-free years owing to major non-communicable diseases
Obesity is known to be associated with an increased risk of several major non-communicable diseases including type-2 diabetes, coronary heart disease, stroke, asthma and several cancers. It was previously thought that metabolically healthy obese (MHO) individuals were at no increased risk of these conditions. MHO is characterised by a healthy blood pressure, low cholesterol, normal insulin regulation and reasonable levels of physical fitness. However, more recent longitudinal studies have found that these individuals show a strong tendency to progress to an unhealthy obese state. What has been relatively understudied is the degree to which obesity is associated with the development of these major non-communicable conditions.
In this large study, published in The Lancet, the health data from 120,181 participants was analysed in order to determine how many disease-free years were lost to obesity. The participants were of a range of BMIs, but free of other comorbidities. They found that overweight patients lost 1 disease free-year, mildly obese patients 3-4 years and the severely obese 7-8 years compared with normal weight participants. Severe obesity was associated with the loss of 7-10 disease-free years in active and inactive individuals; current, past and never-smokers; and those of high and low socioeconomic position. The paper suggests that obesity, even in those with a healthy metabolic profile, leads to a substantial loss of disease-free years, across the social hierarchy and irrespective of lifestyle factors such as physical activity and smoking.
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Contribution of maternal diabetes to visceral fat accumulation in offspring
Epidemiological studies have previously demonstrated the contribution of a genetic background of diabetes to the development of obesity. The goal of this study was to explore the contribution of parental family history of diabetes to visceral fat area. Diabetes and obesity share many overlapping risk factors and genetic architecture, with visceral fat being responsible for many of the comorbidities associated with obesity. This large study, conducted in China, recruited 1875 people, aged 20-78, with normal glucose tolerance. The recruited individuals then had an assessment of their visceral fat accumulation using MRI.
The study found that a maternal family history of diabetes was associated with visceral fat accumulation, independently in both genders. Maternal transmission had a pronounced effect on obesity and related cardiovascular risk factors, however this study does not elucidate the underlying mechanism of this visceral fat accumulation. Despite the lack of understanding of the mechanism, this data can be used to inform public health policies when trying to predict which groups will be most at risk of obesity and its related comorbidities.
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