positive energy balance and disease Flashcards
how many kcal is 1g of fat?
9 kcal
does exercise promote weight loss in obese individuals?
on the whole, no
reasons why exercise doesn’t promote weight loss in obese people?
high-intensity tasks not feasible for those with high BMI and body fat %
gentle physical actvity will expend 500 kcal but will overreat after so wipe out negative caloric deficit
how may the positive effects of exercise be maximised for obese people?
increase in energy expenditure through exercise must be used in conjunction with reduced daily calorie intake
so don’t reverse effects through overreating
what is the main principle of dietary advice given to obese people?
remain in negative energy balance
using more than taking in
how many calories under someone’s energy requirements is suitable for a diet?
600-700kcal
how to determine how much is 600-700 kcal under what someone normally eats?
indirect calorimetry or henry oxford equation -measure basal metabolic rate
calculate energy expenditure
works out energy requirements
what are the components of weight loss?
75-90% adipose tissue
10-25% fat free mass (decreases metabolic rate so have to readjust calculations)
most typical diet?
low energy content diet e.g mediteranean diet
low fat and more mono than saturated
high fibre (low caloric value as don’t digest)
high protein - requires energy to digest
low glycemic foods to reduce insulin levels promoting storage of energy
describe drug treatment for obesity?
orlistat (lipase inhibitor)
- inhibits fat digestion and absorption so calories not stored in body
- side effects of fatty faeces which may stop one eating fat
- 5% weight loss at 3 months
- maintenance rarely achieved
describe bariatric surgery as a treatment for obesity?
restrict amount of energy taken into and aborbed into body
e.g gastric bypass surgery which reduces size of stomach so feel full quickly and moves parts of intestine
reduces energy intake by over 1000kcal a day leading to 30% weight loss in first year
stimulates increased release of ‘full’ hormones so stop feeling hungry
problems with protein malnutrition
describe type 2 diabetes as an energy overnutrition disease?
cause?
damage as a result?
1 in 10
high blood glucose levels (hyperglycaemia) due to insulin resistance so muscles don’t take up glucose properly or instruct liver to stop producing glucose
damages small blood vessels leading to microvascular diseases and large blood vessels leading to macrovascular disease and nerves
caused by positive energy balance NOT obesity
why is type 2 diabetes known as non-insulin dependent?
non-insulin dependent as don’t require more until a few years later when release declines due to excessive release for many years
why don’t all obese people have type 2 diabetes?
morbidly obese store fats within adipose tissue (good)
for others, may store fat in abdominal cavity and liver, whether obese or not
depends on distribution of body fat in wrong places not necessarily how much body fat
why may fat be stored in the liver?
excess chylomicrons from adipose tissue go to liver
released as VLDL
process impaired and more cholsterol synthesis so more LDL
what is the lipid overspill hypothesis?
increase in fat storage or adipose tissue dysfunction then ‘spills over’ to other tissues (incl liver)
begins to interfere with insulin action and tissue becomes more resistant
insulin can’t suppress glycogenolysis and gluconeogenesis in liver which increases blood glucose
also can’t stimulate glucose uptake in muscles
what does glycaemic index of a food relate to?
how to work it out?
relates on its effect on blood glucose
divide area under glucose x time curve for e.g starch and divide by area under curve for glucose then x100
what indicates whether food has low or high glycaemic index?
high >70
low <55
what is the blood glucose response to ingestion of glucose in a regular and type 2 diabetes individual?
regular - levels peak after 30 mins of ingesting and slowly decreases
diabetes - peak is higher and slowly decreases but higher than levels for regular people
what is the diagnosis for fasting blood glucose in type 2 diabetes?
and for 2 hours after ingestion of 75g of glucose?
fasting - >7mmol/l
ingestion - >11mmol/l
what are the nutritional strategies for type 2 diabetes?
reduce energy intake to improve glycaemia, dislipidaemia and blood pressure
knowledge of carbs which are low and high glycaemic index
what has been found about ‘reversing diabetes’?
eating only 600kcals a day
how can exercise lower muscle glucose levels?
muscle contraction stimulates GLUT4 translocation to plasma membrane aiding uptake of glucose into muscles
pathways independent of insulin stimulated glucose uptake so not impaired in diabetes
so exercise lowers blood glucose levels as well as liver and muscle triaglycerol
