popular nutrition myths and diets Flashcards
grapefruit burns fat
no foods can burn fat
grapefruits or an citric fruits being able to burn fat has no scientific proof
based on small number of animal studies which suggest that citric acid inhibits fat synthesis and may suppress appetite. these claims have no validity and are inconclusive in animals let alone humans
low fat means low calories
a low-fat or non-fat food is usually lower in calories than the same size portion of the full-fat product because fat contains more calories p/gram than any other macro.
food manufacturers often add sugar, flour and starch thickeners to improve the flavour and texture of the food once the fat has been removed all these ingredients seek to increase calorific value.
eating in the evening causes weight gain
the time of day that foods are eaten does not affect how that food, or the energy within it, is used.
if the body’s glycogen stores are low and carbs are consumed, the glucose digested and absorbed from those foods will be transferred to muscles and liver for storage as glycogen regardless of time of day.
only when the daily energy exceeds the body’s requirements will foods be converted to fat.
skipping meals is good for weightloss
research has consistently shown that people who skip meals tend to be heavier than people who eat a healthy breakfast and eat 4-5 meals a day.
skipping meals triggers the hunger mechanism and is likely to result in poor food choices and binges later on.
food consumption increases body temperature and metabolism.
weight training is no good for weight loss
this is technically true as combined with a diet rich in protein will lead to increased lean mass.
increased levels of lean muscle tissue have the greatest impact on metabolic rate
while weight training exercises don’t burn fat, they do accelerate metabolism and increase daily energy expenditure
lose 20 pounds in 20 days
a weight loss of 1-2 pounds a week is most effective way to ensure sustainable weight loss and that it is primarily being fat lost.
losing weight so fast will be from water, glycogen and lean body mass.
because these diets are always based on calorie restriction, they reduce metabolism rather than promoting it
fat people have slower metabolism
heavier people always expand considerably more energy than lighter individuals at rest and during comparable physical activities
eating fat makes you fat
the consumption of fat doesnt make an individual gain weight, rather it is the overconsumption of energy that is responsible for this.
because each gram of fat contains 2.25 times the number of energy that carbs and protein contain, it is much easier to exceed the daily energy needs with foods containing fat.
the weekend off approach
letting yourself off for the weekend is flawed because considerably more calories than the body actually needs are likely to be consumed. if the deficit created during the week is equal to the excess achieved over the weekend, bodyweight will remain stable.
if even weight loss does occur it is still not healthy one because it is not balanced and weight loss is likely to be lean tissue and water.
set point theory
explained why repeated bouts of dieting were unsuccessful in creating a permanent change in bodyweight.
the set point theory claims that there is an internal control system that is built into each person and that this system dictates how much fat they should carry and store.
if this were true then people with chronic illness and disease who are physically incapable of exercising would not be able to improve their condition by improving their nutritional habits/ also, those who have struggled to manage their bodyweight have the perfect excuse as to why there is little point in improving their eating habits.
atkins diet
4-phase weight loss programme that permits an unlimited amount of high fat and protein foods, but restricts the amount of carbs that can be eaten.
foods allowed on atkins diet
meat eggs cream cheese shellfish butter some vegetables
foods not allowed on atkins diet
processed meats breads grains pasta and rice potatoes margarine most vegetables
Dr Atkins’ primary justifications for his diet
- when carbs are frequently ingested, an over production and release of insulin occurs which results in greater levels of hunger, over-eating and weight gain.
- when foods high in fat and protein are consumed, insulin levels remain low and appetite is supressed because they foods create satiety. usually results in less kcal being consumed overall and weight loss is evitable.
- insulin increases the activity of the enzyme lipoprotein lipase, which is responsible for the storage of fat in muscles and adipose tissue. if insulin levels are kept low, the activity of this enzyme and any subsequent fat storage will also be reduced.
- ketosis increases fatty acid mobilisation; not only is less fat stored, but higher levels of fats are burned because carbs are not available.
- the greater thermic effect of protein and fat reduces the net energy available from the digested foods, compared with the same energy intake from carbs sources. thus the body has to do considerably more work to free the energy contained within the food, reducing the energy that is available for storage following digestion and absorption.
key health risks from atkins
high fat and protein diets often contain large quantities of saturated fats, which increase the risk of heart disease and type 2 diabetes
- diets high in animal fat increase the excretion of a compound called oxalate in the urine. oxalate combines with calcium in the kidneys to form kidney stones.
- ketosis is a form of acidosis and can, if sustained over a long period of time, reduce the body’s ability to manage the acidity of the blood; in extreme cases can lead to blood poisoning.
- the diet is deficient in fibre and promotes dehydration which can increase the potential for constipation and other digestion tract disorders
- not suitable for vegetarians
- diet is deficient in many key vitamins, esp antioxidants and phytochemicals.
- cost of the diet is expensive and would not be practical for the masses. if it were to be adopted universally there would be insufficient food available for the world.
- boredom is common because food choice is restricted
- not suitable for athletes or regular exercises because carbs needed.
