Extra reading lecture 7

Question 1

variety review-

Answer 1

Johnstone and Wardle 2014= variety and palatability are risks for obesity. The increase in variety in supermarkets and restaurants increases this!

They explained how- Suggest, training in cognitive and behavioral strategies may be possible to help individuals to increase their resilience. Increasing awareness by educating people about the effects of palatability and variety on tendency to overeat, and providing them with the skills to counter these effects, might offer some protection against continuing weight gain. People need to change their environent, to reduce exposure to a variety of energy dense foods

However they argue, that putting the blame onto the overweight people themself may not be a good method, and we may need to tackle the environment face on instead

Johson Pratt and Wardle 2012= Recent research highlighted the potential for training to enhance self-regulation in the face of tempting food environments, Braet 1997= children who learn/taught self regulation have lower weight, and weight loss

Rolls 2012= study showed a greater variety of avaialbale fruits and veg led to an increase in consuming these. Rolls suggested from this, perhaps from restricting our exposure to energy dense foods, we should stock our cubaords with low energy, nutrtious but VARIED and appealing foods- (economic issues!)

Question 2

Portion sizing

Answer 2

Rolls et al., 2004= portion size of pasta in cafeteria was increased by 50%, people percieved this as the same, and almost all people ate more.
Some food is more succeptible tothis portion size effects such as foods with distinct shapes, like pasta, where it is difficult to differntiate sizes, and whole units such as bars and sandwhcihes . AND is strongest for foods that are best liked(rolls et al., 2004)

Combating the portion size effect=

Question 3

Dietary variety: and SSS

Answer 3

Rolls 1981= labatory study showed people ate more food with a plate of food with lots of variety than during a meal with a single food

Johnstone and wardle 2014- show how this variety effect affects people regardless of weight stature=

Rolls 1986= palatability decreases known as SSS, this promotes consumption of other foods.

Johntone et al., 2001- access to greater variety of food an beverages with different sensory properties led to an suistained increase in energy intake over 7 days.

HOWEVER Rolls 2018- highlights how this relationship is only seen with high energy dense foods. e.g. SSS and increase in variety can cause increase in intake of high energy dense foods which is associaed with obesity. But other SSS shows an increase in variety of nutritonal and low energy dense foods and this is associated with lower body weight- this suggests maybe interventions should use this research, to promote variety diets/meals with low density foods. This may explain why certain diets dont work e.g. diets which ask people to eat the same low energy foods day after day….. people crave SSS and variety! create healthy meals with lots of variety!

Raynor et al., 2004= 18 month clinical trial= greater weight loss was observed with people who had an increae in variety of vegetables, and a decrease in variety of high energy dense foods.

Vadevilo 2016= 2 year trial, found increase in variety of healthy foods,a nd decrease in adiposty

Question 4

using sensory specific satiety

Answer 4

Rolls 2018- highlights how this relationship is only seen with high energy dense foods. e.g. SSS and increase in variety can cause increase in intake of high energy dense foods which is associaed with obesity. But other SSS shows an increase in variety of nutritonal and low energy dense foods and this is associated with lower body weight- this suggests maybe interventions should use this research, to promote variety diets/meals with low density foods. This may explain why certain diets dont work e.g. diets which ask people to eat the same low energy foods day after day….. people crave SSS and variety! create healthy meals with lots of variety!

Roe et al., 2013- variety of vegetables for preschool children increased consumption of overall veg- extraplorating SSS!

Question 5

definition for sensory specific satiety

Answer 5

“Sensory-specific satiety describes the decline in pleasantness associated with a food as it is eaten relative to a food that has not been eaten.” (Wilkinson & Brunstrom, 2016).

Question 6

top down vs top up processes

Answer 6

Higgs et al., 2016
Found in amnesic patients SSS still occurred, despite them not remembering if they ate. This often led to overconsumption in amnesic patients-
However it tells us SSS is not just driven by top down cognitive processes such as habituation or conciously considering the availability of other foods.
But that it is also driven by bottomo up proceses such as neurophysiological responses including a decrease in OFC neuronal response as the same food is eaten AND OTHER physiological post absorbive effects(more biological) (Rolls 1986)

HOWEVER, studies show even tasting a food but not actually consuming a food causes SSS, suggesting it is a mechanism of sensory attributes rather than biological post absorbtive effects

with these contrasting results it is best to suggest SSS is as a result of both habituation, monotomy, and physiological processes.