obesogenic environment to obesity Flashcards
Behavioural theories- physical activity
increase in obesity may correlate with decrease in daily energy expenditure. May be due to imporvements in transport systems, shift from agricultural society to an industrial one.
Prentic and Jebb 1995- strong association between an increase in car ownership per household and tv viewing per week and an increase in obesity, so we could conclude low physical activity is linked to an increase in obesity. However this is only correlational, so the argument remains unclear, another variable may be determining both obesity and activity (third factor problem). This research also misses individual differences
Haapenen et al., 1997= monitored 5,000 working adults over a 10 year period and found those who reported no physicall activity at baseline and follow up, were twice as likely to have gained more than 5kg over the 10 years than those who reported two sessions of vigorous activity per week.
A link between sedentary lifestyle and weight gain in children has also been shown, using tv viewing as a measure of activity (Gortmaker et al., 1996)
Waller et al., 2008= 30 year longitudinal twin study. in 42 twins discordant in physical activity, weight gain and waist circumference was correlated with physical activity. Smaller waist circumference and a decreased weight gain was related to persistent physical activity. Active twin compared to inactive twin has a smaller circumference, despite having the same genetic make up.
obese exercise less
OBESE EXERCISE LESS- Bullen, Reed and Mayer 1964- in girls camp the obese girls spent less time swimming and more time floating, and while playing tennis the obese girls were inactive for 77% of the time compared to normal weight girls who were inactive for 56% of the time.
however is this a cause or a consequence? Lots of research has also found obese people tend to exercise less. Schoeller 1994 found high correlations between percentage body fat and energy expenditure, and other studies showed obese people tend to avoid stairs and exercise less . Also these studies are often longitudinal, third factors such as pregnancy and general weight gain from having a child are not accounted for.
Again is this causation or consequence? Atlantis, Barnes and ball 2008, found overweight perception was found to be a strong barrier to physical acitivity, and the obese exercise less due to other factors including embarassment and stigma.
behavioural theories- eating behaviour
why do the obese chose to eat?
eating behaviour includes beliefs about food, family food habits, childhood etc..
Why do the obese chose to eat?- Obese people were found to eat due to internal and external cues, but were overresponsive to external cues where as normal weight individuals mainly ate because of internal cues (satiation, hunger) Schacter 1968
Schacteret al., 1974, also developed the emotionality theory of obesity, arguing obese people are not just more responsive to external cues, but they also ate more than nonobese in response to emotions such as anxiety, fear, boredom, depression. Bruch 1974, explained how some people interpret emotions as an emptiness similar to the feeling of hunger, and they therefore chose to eat.
More emotions and eating- Strein et al. 2008= they argue that emotional eating is a better predictor of body weight than external eating. Macht 2008 t way model ( on other card)
One study by Arce et al. (2021) investigated the role of external eating and inhibition problems in children and adolescents with obesity. It found that those who are more responsive to external cues tend to have higher weights, supporting Schachter’s findings from the 1960s and 1970s regarding the influence of external stimuli on eating behavior.
do the obese actually over eat?
Do the obese actually overeat? research has found that obese people dont actually consume more food (Jeffery and wing 1978) and Sptzer and Robun 1981 examined 29 studies and found only 9 reported overweight subjects actually ate more food than non overweight people. However there are issues here, such as self reporting measures. Jebb et al 1996- found in controlled conditions if obese and nonobese are overfed or underfed they lose and gain weight at the same Weight, suggesting they must be eating more.
Type of food consumed may be a better predictor- emphasis on the ratio between carbs and fat. Prentice and Jebb 1995 found humans eat more fatty diets than they used to. so the obese may eat more fat, not necessarily more food? Calories are also not equal, calories from fat may lead to greater weight gain.
changes in food intake
Changes in food intake- Concurrent to the increase in obesity there has been a significant increase in sweetened drinks consumed (sturm 2008). Research shows habitual consumption of these drinks is a significant predictor of weight gain (Raben et al., 2003)
price of fresh produce has increased while the price of confectionary has decreased, leading to people making cost effective decisions and eating more unhealthy food.
Jekanowski 2001 reported that people now eat out much more, and food on offer is higher in fat, and takes less effort to prepare and in larger portions (Prentice and Jebb 2003)
The modern diet is characterized by the absence of foods rich in micronutrients (Popkin et al., 2005)
people don’t necessarily eat more but eat differently.
Emotional eating and obesity
More emotions and eating- Strein et al. 2008= they argue that emotional eating is a better predictor of body weight than external eating. Macht 2008 t way model ( on other card)
Additionally, research by Lanza et al. (2021) examined emotional eating during the COVID-19 pandemic and its effects on weight. They found that emotional eating behaviors, including eating in response to stress, were prevalent among individuals with higher body mass indices (BMIs). This aligns with earlier theories suggesting that obese individuals may eat more due to emotional states like anxiety and boredom
eating behaviour part 2-fat proportion theory
Type of food consumed may be a better predictor- emphasis on the ratio between carbs and fat. Prentice and Jebb 1995 found humans eat more fatty diets than they used to. so the obese may eat more fat, not necessarily more food? Calories are also not equal, calories from fat may lead to greater weight gain.
Bolton-smith an woodward 1994= found men consuming the lowest proportion of carbs in their diet were 4x more likleu to be obese, similar in women- concluding a relatively higher carb diet is related to lower levels of obesity.
Fat proportion theory- eat more fat than carb, not just more fat, or more food. its the ratio of fat to carbs (Blundell and Macdiarmid 1997)- they found high fat eaters who derive 45% of energy from fat were 19!! times more likely to be obese than those who derived less than 35% of their energy from fat
Blundell et al., 1996-1997=
benefits in complex carbs in energy use-takes more energy to burn carbs than fats so we have energy for longer in a carb rich diet. Carbs are burned, but fat is stored. Complex carbs also reduce hunger due to fibre content, therefore reducing food intake. Fat does not switch off the desire to eat so a more fat rich diet just makes you want to eat more and more fat without feeling full.
eating behaviour part 3- dieting and obesity
dieting can actually be a cause and consequence of obesity- because obese people often go on diets, however diets may actually cause weight gain also….
diets ma create fluctuated episodes of overeating, and also undereating
Herman et al., 1991= weighed 24 restrained and unrestrained subjects over time and found restraint was a better predictor of weight. suggesting that episodes of under and overeating resulting from dieting are translated into fluctuations in weight.
French et al., 1994- hisotry in dieting, current dieting, and previous involvement in weight loss programms were related to higher body weight in men and women. dietry restraint is therefore linked with weight fluctuation.
why are people eating larger sized meals
Wansink and van Ittersum (2013): Their research examined how portion sizes have increased in both home-cooked meals and restaurant servings. The authors pointed out that the average serving sizes for various food items have risen dramatically over the years, contributing to overconsumption
Geier, Rozin, & Doros (2006) introduced the concept of unit bias, showing that people tend to consume the entire “unit” of food provided (whether it’s a portion, pack, or serving size), leading to overconsumption when portions are large. larger portions lead to increased calorie intake
