If you're struggling to lose weight, it might actually be due to a chemical imbalance in your brain.
Researchers at the National Institutes of Health have shown that some obese individuals might have differences in the reward areas of the brain, compared to non-obese individuals.1 The ability to resist the urge to eat needs to be stronger than the expected feeling of reward when we do eat. Some people seem to have an impairment in the brain area associated with reward sensitivity, and therefore their willpower is overwhelmed by the need to get that food reward.
[I wish this paper were open access as I'd love to know whether the researchers think one could break the conditioned response!]
1Volkow ND, Wang GJ, Baler RD. Reward, dopamine and the control of food intake: implications for obesity. Trends Cogn Sci. 15:37-46 (2011).
Showing posts with label diet. Show all posts
Showing posts with label diet. Show all posts
Sunday, 23 January 2011
Saturday, 25 September 2010
Rubbish! Chilis don't make you lose weight! ...or do they?!
Research on the effect of chili peppers on metabolic rate, continues.
In a study done at McMaster University in Canada, researchers tested the effect of capsinoids (substances present in chili peppers, and related to the more famous compound capsaicin) on energy expenditure, fat burning, and levels of certain molecules in the blood.1
Twelve healthy male subjects were observed before and after a 90 minute stationary bike ride. During two separate experiments all subjects took (randomly) either a placebo or a treatment containing 10mg capsinoid, so that each subject had results that represented the effect of capsinoids and the effect of placebo. The subjects were tested with respect to oxygen consumption, respiratory exchange ratio (RER), heart rate, perceived exertion, and blood metabolites. Previous research on other andrenergic agonists (like caffeine) showed that these variables are changed by the treatment both during rest and during exercise. However, in the current study effects were mainly significant during rest. The main findings in this study were that, versus a placebo, 10 mg of capsinoids induced a rise in resting oxygen consumption, a decline in RER, an increase in plasma norepinephrine, and a decline in serum free fatty acids at rest. 10 mg of capsinoids also blunted the small but significant rise in blood lactate observed at the onset of exercise seen in the placebo group (0 mg).
This means that capsinoids raise the resting metabolic rate (shown as an increase in oxygen consumption) without increasing resting heart rate (none were observed in the study). Furthermore, the increase in norepinephrine and decline in RER suggest that the body burns more fat at rest. However, the effect of capsinoids on metabolism didn't carry over into exercise, where both groups showed similar metabolic states.
Capsinoids, therefore, represent a useful treatment for patients who want to lose weight, regardless of their level of physical activity.
1 Josse et al. Effects of capsinoid ingestion on energy expenditure and lipid oxidation at rest and during exercise. Nutrition & Metabolism 7: 65 (2010).
In a study done at McMaster University in Canada, researchers tested the effect of capsinoids (substances present in chili peppers, and related to the more famous compound capsaicin) on energy expenditure, fat burning, and levels of certain molecules in the blood.1
Twelve healthy male subjects were observed before and after a 90 minute stationary bike ride. During two separate experiments all subjects took (randomly) either a placebo or a treatment containing 10mg capsinoid, so that each subject had results that represented the effect of capsinoids and the effect of placebo. The subjects were tested with respect to oxygen consumption, respiratory exchange ratio (RER), heart rate, perceived exertion, and blood metabolites. Previous research on other andrenergic agonists (like caffeine) showed that these variables are changed by the treatment both during rest and during exercise. However, in the current study effects were mainly significant during rest. The main findings in this study were that, versus a placebo, 10 mg of capsinoids induced a rise in resting oxygen consumption, a decline in RER, an increase in plasma norepinephrine, and a decline in serum free fatty acids at rest. 10 mg of capsinoids also blunted the small but significant rise in blood lactate observed at the onset of exercise seen in the placebo group (0 mg).
This means that capsinoids raise the resting metabolic rate (shown as an increase in oxygen consumption) without increasing resting heart rate (none were observed in the study). Furthermore, the increase in norepinephrine and decline in RER suggest that the body burns more fat at rest. However, the effect of capsinoids on metabolism didn't carry over into exercise, where both groups showed similar metabolic states.
Capsinoids, therefore, represent a useful treatment for patients who want to lose weight, regardless of their level of physical activity.
1 Josse et al. Effects of capsinoid ingestion on energy expenditure and lipid oxidation at rest and during exercise. Nutrition & Metabolism 7: 65 (2010).
Monday, 2 August 2010
Obesity - disease or lack of willpower?
Debate rages over whether obesity is caused by lifestyle or is actually a disease.
A lot of research has pinpointed genetic factors that are associated with obesity and even some behaviours. Certain changes in DNA are strongly correlated with the incidence of obesity, such as the deletion of DNA from chromosome 161 and specific changes in single nucleotides in 13 different genes in the human genome.2 A research group in Spain has found a strong association between single nucleotide polymorphisms (SNPs) in a gene related to the circadian clock3, and cessation of a weight-reduction program. These SNPs were also associated with extreme snacking, eating when bored, skipping breakfast, and abdominal obesity.
The value of this research lies in the potential to tailor weight-loss programs to the individual. At the Nutrition, Physical Activity, and Metabolism 2010 conference held in March in San Francisco, data was presented showing that people responded better to diets when these diets were assigned based on their genotype, instead of randomly.4
Subjects were put on either the Atkins, Ornish, Traditional, or Zone diets, and the presence of specific forms of three different genes were determined. There was a strong and significant correlation between certain genotypes, a specific weightloss regime, and amount of weight lost. The proportion of people who responded well to low-carb diets compared to those who responded well to low-fat diets was approximately 50-50.
So your genes might tell you whether you're predisposed to gaining weight. It can also help you to choose strategies to manage weight loss. Increasing knowledge of the links between genes and disease allow for the development of more sophisticated drugs and treatments.
1Walters R.G. et al. A new highly penetrant form of obesity due to deletions on chromosome 16p11.2. Nature 463, 671-675 (2010).
Source
2Cheung C.Y.Y. et al. Obesity Susceptibility Genetic Variants Identified from Recent Genome-Wide Association Studies: Implications in a Chinese Population. The Journal of Clinical Endocrinology & Metabolism 95: 1395-1403 (2010).
Source
3Garaulet M. et al. PERIOD2 Variants Are Associated with Abdominal Obesity, Psycho-Behavioral Factors, and Attrition in the Dietary Treatment of Obesity. Journal of the American Dietetic Association 110: 917-921 (2010).
Source
4O'Riordan M. Dieting by DNA? Popular diets work best by genotype, research shows. Heartwire (2010)
Source
A lot of research has pinpointed genetic factors that are associated with obesity and even some behaviours. Certain changes in DNA are strongly correlated with the incidence of obesity, such as the deletion of DNA from chromosome 161 and specific changes in single nucleotides in 13 different genes in the human genome.2 A research group in Spain has found a strong association between single nucleotide polymorphisms (SNPs) in a gene related to the circadian clock3, and cessation of a weight-reduction program. These SNPs were also associated with extreme snacking, eating when bored, skipping breakfast, and abdominal obesity.
The value of this research lies in the potential to tailor weight-loss programs to the individual. At the Nutrition, Physical Activity, and Metabolism 2010 conference held in March in San Francisco, data was presented showing that people responded better to diets when these diets were assigned based on their genotype, instead of randomly.4
Subjects were put on either the Atkins, Ornish, Traditional, or Zone diets, and the presence of specific forms of three different genes were determined. There was a strong and significant correlation between certain genotypes, a specific weightloss regime, and amount of weight lost. The proportion of people who responded well to low-carb diets compared to those who responded well to low-fat diets was approximately 50-50.
So your genes might tell you whether you're predisposed to gaining weight. It can also help you to choose strategies to manage weight loss. Increasing knowledge of the links between genes and disease allow for the development of more sophisticated drugs and treatments.
1Walters R.G. et al. A new highly penetrant form of obesity due to deletions on chromosome 16p11.2. Nature 463, 671-675 (2010).
Source
2Cheung C.Y.Y. et al. Obesity Susceptibility Genetic Variants Identified from Recent Genome-Wide Association Studies: Implications in a Chinese Population. The Journal of Clinical Endocrinology & Metabolism 95: 1395-1403 (2010).
Source
3Garaulet M. et al. PERIOD2 Variants Are Associated with Abdominal Obesity, Psycho-Behavioral Factors, and Attrition in the Dietary Treatment of Obesity. Journal of the American Dietetic Association 110: 917-921 (2010).
Source
4O'Riordan M. Dieting by DNA? Popular diets work best by genotype, research shows. Heartwire (2010)
Source
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