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    THERMAL RESPONSE TO FAT, CARBOHYDRATE AND PROTEIN


    INTRODUCTION

    Thermogenesis = increase heat production to maintain body temperature by shivering or in response to food that causes diet induced thermogenesis.
    The vast majority of people in the UK can eat as much food as they desire but the was not the case in the past when famine was more common. To combat this the human body has evolved to find a way of storing energy from the food eaten. As fat a has the potential to release the most energy per (39.1 kJ/g) over alcohol (29.75 kJ/g), protein (18.5 kJ/g), starch (17.6 kJ/g) and glucose (15.4 kJ/g). The body has developed metabolic pathways to store as much of this energy as possible for time of starvation. To get the greatest yield of energy from fat, as little of the fat has to be oxidised as possible therefore lowering the amount of thermogenesis that occurs. The body is not capable of storing vast quantities of protein and carbohydrate relative to fat as it takes 2 grams of either to make 1 gram of fat, add to that the metabolic conversion, which uses about a quarter of the calories contained as excess.
    Besides being difference in metabolism between each macronutrient there is individual difference with in a macronutrient as sugar mixed with water provides more energy and puts on more body fat than sugar eaten by itself in the same amount.
    There are various factors that effect the metabolic rate that are: -
    Weight an increase in weight causes a increase in metabolic rate though this is often as a weight increase coincides with a increase in lean body mass as muscles require more energy than fat mass.
    Age; as you age you require less energy per kg of body weight though this is often as children require more energy for growth and have a greater amount of lean body per kg of body weight.
    Gender, males frequently have a higher metabolic rate than females however, this is often as males have more lean body mass than females.
    Beta agonists - these increase thermogenesis by stimulating adipose tissue to release stored fat into the blood stream that is then oxidised.
    Thyroid hormones stimulate the metabolism, which cause an increased conversion of carbohydrate, fat and protein. The greater the levels the greater thermogenesis is.

    AIMS

    0) To find out whether fat, protein or carbohydrate increase the metabolic rate the therefore increasing thermogenesis.
    0) To find out if any other variables tested might effect thermogenesis
    0) To improve knowledge of statistics when analysing data





    METHODOLOGY

    To determine the metabolic rate, o₂% and volume of air expired must be known.
    The subjects were in the period of early starvation, as food was not consumed since the previous day. This allowed the starvation metabolic rate to be measured.
    How the metabolic rate was measured.
    1) Subjects are seated then will breath into a mouthpiece that is connected to a Douglas bag. This will last for 5 minutes. Then the mouth piece is removed
    1) Siphon air from the Douglas bag into a 1-litre bag. This bag is then sampled for o₂% (Oe) using an o₂ analysing machine.
    1) With the remaining air, measure this through a gas meter to find the volume of air expired. Add 1 litre to this volume to get total volume of air expired (Ve).
    1) Barometric pressure and room temperature should be noted. Saturated vapour pressure of water at (SVP (water)(t)) should be read from nomogram.

    The equation to work metabolic rate is

    1) correct Ve to STP dry:-

    Ve (corr) = Ve*273/(273+t)*(Pb-SVP)/760 dm³

    1) using weir’s formula:

    Kcal/dm³ of exp air (STP dry) =1.046-0.05*Oe =E

    1) kcals/5 mins = Ve (corr) (dm³) * E

    1) calculate kcal for day

    Kcal/ 24 hours = kcals/5 mins*12*24 = RMR



















    KEY + CALCULATIONS

    45% = the percentage increase of thermogenesis after 45 minutes = 100/MR45*FMR2
    -100.
    90% = the percentage increase of thermogenesis after 90 minutes = 100/MR90*FMR2
    -100.
    MR45-FMR2 = the difference between fasting metabolic rate and metabolic rate after
    45 minutes.
    MR90-FMR2 = the difference between fasting metabolic rate and metabolic rate after
    90 minutes.
    FMR2 = fasting metabolic rate. If FMR2 was not given, FMR1 was moved into
    FMR2.
    MR45 = the metabolic rate after 45 minutes
    MR90 = the metabolic rate after 90 minutes.

    For t-test

    To keep the assignment brief only one null hypothesis was wrote instead of three.
    E.g. H0: = there is no significant difference between FMR2 between the two nutrients.
    H1: = there is significant difference between FMR2 between two nutrients.
    To write H0: = there is no significant difference between carbohydrate and proteins
    FMR2
    H1: = there is significant difference between carbohydrate and proteins FMR2
    Then two write that for the further other two combinations for all of the t-test would increase the word count by 500 words therefore making the assignment bogged down.
























    RESULTS AND DISCUSSIONS

    The most important finding from the results is that within in the group (table 1)

    MEAN MEDIAN MAX MIN MAX MIN
    NUTRIENT 45 MINS 90 MINS 45 MINS 90 MINS 45 MINS 90 MINS
    CARBOHYDRATE 282 380 173 323 767 73 1240 43
    PROTEIN 387 426 354 413 931 77 937 66
    FAT 154 137 152 155 362 -60 279 -135
    (See appendix 1)

    45 minutes = MR45-FMR2
    90 minutes = MR90-FMR2

    Protein had the highest means and medians after 45 and 90 minutes after eating. This shows on average protein causes the largest growth in thermogenesis, however carbohydrate caused the largest individual response in a single individual of a difference of 1240 kcal after 90 minutes.
    Fat had the lowest means and medians after 45 and 90 minutes. Showing that fat causes a smaller change in metabolic rate than the other two nutrients.
    Below are the results from the t-tests.

    Table 1 showed difference in thermogenesis but this would not be a fair test if starting metabolic rates are different the below table work that out.

    H0: = there is no significant difference between FMR2 between the two nutrients.
    H1: = there is significant difference between FMR2 between two nutrients.

    Table 2
    Nutrient tested Test statistic Critical value p value Significant difference
    Carbohydrate-protein 0.47 2.11 0.65 No
    Carbohydrate-fat 0.57 2.11 0.58 No
    Protein-fat 1.17 2.10 0.25 No
    (See appendix 2)

    All H0: are accepted and H1: may be rejected.
    From the result of this, there is no significant difference between any two of the nutrients before the foods are consumed. This means none of the nutrient is at a disadvantage as increased starting metabolic rate means the individual has a higher BMI (r=0.686434 this is the correlation between BMI and FMR2 this exceeds the C.V. of 0.355 therefore can conclude that there is an association between a higher BMI and increased FMR2). The higher the starting BMI the greater the increase in thermic response is (at MR45 r=0.479813 and at MR90 r=0.487838 the Critical value is 0.355 which both r value exceed hence can conclude there is an association between increasing the BMI increase the thermic response).
    So if there is a significant difference after 45 or 90 minutes after eating the increase in thermic response can be attributed to the nutrient eaten.

    This table below shows if the increase in thermic response after 45 minutes following consuming the nutrient.

    H0: = there is no significant difference between MR45-FMR2 between the two
    nutrients.
    H1: = there is significant difference between MR45-FMR2 between two nutrients.

    Table 3
    Nutrient tested Test statistic Critical value p value Significant difference
    Carbohydrate-protein 0.89371 2.14 0.39 No
    Carbohydrate-fat 1.40915 2.10 0.18 No
    Protein-fat 2.60810 2.10 0.018 Yes
    (See appendix 3)
    The Carbohydrate-protein and Carbohydrate-fat groups can both accept the null hypothesis (H0, as there is no significant difference between the two groups. From this it can be determined that the difference between the thermic response of “carbohydrate and protein” and “Carbohydrate and fat” does not cause a great difference on average between the two nutrients after 45 minutes.

    For “Protein and fat” group (H1 can be accepted therefore it can be determined that there is significant difference between the protein thermic response after 45 minutes (MR45-FMR2 protein only values) eating than over fat thermic response (MR45-FMR2 fat only values) after 45 minutes after eating. From this it information it can be determined that after 45 minutes protein has a greater increase on average thermic response than fat as the mean is greater (see table1).

    This table below shows if the increase in thermic response after 90 minutes of ingesting the nutrient

    H0: = there is no significant difference between MR90-FMR2 between the two
    nutrients.
    H1: = there is significant difference between MR90-FMR2 between two nutrients.

    Table 4
    Nutrient tested Test statistic Critical value p value Significant difference
    Carbohydrate-protein 0.30766 2.14 0.76 No
    Carbohydrate-fat 2.13671 2.10 0.046 Yes
    Protein-fat 3.25496 2.10 0.0042 Yes
    (See appendix 4)

    The “carbohydrate and protein” group (h0 can be accepted, therefore there is no significant difference between the average thermic effect of protein and carbohydrate after 90 minutes.
    For “Carbohydrate and fat” and “Protein and fat” (H1 can not be rejected and consequently determine that both carbohydrate and protein have a significantly different thermic effect than fat after 90 minutes following eating. As protein and carbohydrate have a greater average thermic effect than fat it can be determined that carbohydrate and protein cause a greater increase in thermogenesis than fat.
    After 90 minutes the p value decreased while the critical value increased for “carbohydrate and protein” while the gap between there means decreased it can deduced that protein increase thermogenesis more rapidly than carbohydrate which takes more time to have such a large effect on thermogenesis.
    The above deduction is backed up by after 90 minutes there is now significant difference between carbohydrate and fat effect on thermogenesis, as fat mean stayed roughly the same while carbohydrate mean increased.
    From this fat has the least effect on thermogenesis while protein has the greatest.

    This experiment is not as clear-cut as these results show as there are many variables that can effect metabolic rate. Height, weight, sex and %change over difference may effect thermic response as well.

    As stated earlier an increase in BMI increased the thermic effect of food. But does the thermic effect of food increase in proportion to the size of the individual.

    H0: there is no association between BMI and thermic effect.
    H1: there is association between BMI and thermic effect.

    Table 5
    FMR2 MR45-FMR2 MR90-FMR2 45% 90%
    CORRELATION r= 0.639 0.47 0.48 0.1825 0.317
    CRITICAL VALUE 0.355 0.355 0.355 0.355 0.355
    SIGNIFICANT ASSOCIATION YES YES YES NO NO
    (See appendix 5)

    For FMR2 there is association (accept H1 between increasing BMI and increased FMR2.
    For MR45-FMR2 and MR90-FMR2 there is association (accept H1 between thermic effect and BMI. As it positive increase, an increase in BMI increases thermogenesis.
    For 45% and 90% (H0 can not be rejected and therefore conclude that an increase in BMI is not associated with a percentage increase in thermogenesis relative to the size of the individual.
    A small person actual increase in thermic response may be small but the percentage increase will be the same as a person with a higher BMI even though this person with a high individual had a greater increase in thermic response.












    As mentioned under table 5 there is association between an increased BMI and increased effects of thermogenesis following eating. If i.e. protein group had the highest BMI it might not be surprising that protein caused the greatest thermic effect.

    H0: = there is no significant difference between the BMI of two different nutrients.
    H1: = there is significant difference between BMI of two different nutrients.

    Table 6
    BMI Test statistic Critical value p value Significant difference
    Carbohydrate-protein 0.37492 0.37 0.71 No
    carbohydrate- fat 1.53375 1.53 0.14 No
    Protein - fat 1.240337 1.24 0.23 No
    (See appendix 6)

    All the groups can accept (H0 and therefore conclude that there is no significant difference between the BMI’s of different nutrient groups.

    The table below is information on the BMI between nutrient groups.

    Table 7
    Nutrient mean Median Standard deviation
    Carbohydrate 25.20 22.64 5.89
    Protein 24.27 22.54 4.64
    Fat 22.37 22.58 2.24
    (See appendix 7)

    Carbohydrate may have the largest mean and fat the smallest nevertheless all 3 three nutrients have very similar medians hence from the table 6 and no significant difference among them it can be determined that there is an even mixture of BMI’s amongst the three nutrient groups. BMI does have an effect on thermogenesis however its effect should be cancelled out due to it is fairly split through out the nutrients.

    How does gender effect the thermic response regardless of which nutrient they consumed.

    H0: there is no difference between males and females metabolic rates.
    H1: there is a difference between male and females metabolic rates.

    Table 8
    Time Gender difference Test statistic Critical value p value Significant difference
    FMR Male-female 5.50 2.04 0.0000 Yes
    MR45-FMR 2 Male-female 1.385922 2.04 0.096 No
    MR90-FMR2 Male-female 2.055179 2.04 0.049 Yes
    45% Male-female 0.01 2.04 0.99 No
    90% Male-female 0.95 2.04 0.35 No
    (See appendix 8)

    For FMR2 (H1 is accepted, therefore is a significant difference between males and females FMR2. From the p value there is a very large difference. The r-value is r = -0.720 which is exceeds the critical value of 0.355 therefore males are associated with a higher BMI on average.
    At 90 minutes after consuming food (H1 can be accepted and therefore deduce that there is a difference in thermic effect of food with. As males have the highest mean (table 10) males have the greater thermic effect.
    45% and 90% groups accept (H0 and therefore conclude that males and females thermogenesis increase by the same percentage.
    From table 10+11+12 males have a significantly higher BMI. Though males have a significantly higher BMI (from table 5) a higher BMI increase overall thermogenesis but a high BMI does not have significant difference in percentage increase to that of a low BMI. From this it can be determined that the reason for males having a higher level of thermogenesis but the percentage increase is not significantly different is to do with the BMI rather than gender.

    Table 9
    Nutrient No. of males No. of females
    Carbohydrate 2 7
    Protein 3 6
    Fat 3 9

    The consequences of this are that the fat group has more females in it than the other group consequently this could be a reason why the fat group had lower amounts of thermogenesis than the carbohydrate and protein groups. But as females have the same percentage increase as females this should not effect the levels of which fat increased the percentage of thermogenesis and effect overall results.

    The table is for mean values between males and females

    Table 10
    Gender FMR2 FMR2-MR45 FMR2-MR90 45% 90%
    Male 2518 382 464 13.9 19.3
    female 1689 222 236 13.8 14.0
    (See appendix 10)

    Though males have an increased level of diet induced thermogenesis their percentage increases show no significant difference (Table 8).

    H0: there is no significant difference males and females BMI’s
    H1: there is significant difference males and females BMI’s

    Table 11
    Gender difference Test statistic Critical value p value Significant difference
    male-female 2.94 2.05 0.0065 Yes
    (See appendix 11)

    From this (H1 can be accepted and therefore conclude that there is significant difference between male and females BMI.




    Table of comparison of male verse female’s BMI results.

    Table 12
    Gender MEAN median standard deviation
    Males 27.2 26.7 4.6
    Females 22.5 22.3 3.6
    (See appendix 12)

    The main difference between males and females is that males have a BMI is 4.7 points higher so this will result in a greater increase in thermic effect of food as an increase in BMI increase the amount of thermogenesis. This is evident as from table 10.
    The difference between male and females BMI is significant with males having a higher BMI this can explain why males had a greater level of thermogenesis while the percentage increase did not have a significant difference (table 10)

    From above it is clear that different nutrient effect thermogenesis in different ways. In the experiment the nutrient are consumed during the stages of early starvation.
    Each nutrient has a separate biochemical pathway involved in their metabolism.
    The reason protein increase thermogenesis the most is that protein oxidation as it involves prior conversion to glucose and the formation or urea. This means that more energy is required to produce the equivalent amount of ATP formed from protein than from fat or carbohydrate (stock and rothwell1982) .
    When fat is consumed the release of insulin in response to the meal will increase the activity of lipoprotein lipase that increase the uptake of fatty acids and decrease the metabolic rate therefore reducing thermogenesis as it deposit as much fatty acids in the adipose tissue as possible. Of the energy fat provides, only 2-4% must be used to process it or store it. Carbohydrate requires more energy to process whether oxidised (7%); stored as glycogen (5%); or stored as fat (23-52%). (Kirksey and Haff 1999)
    BMI increased the metabolic rate coincides with department health (1991) equation for predicting metabolic rate of for males 18-29 years old.
    BMR (MJ/day) = 0.063(Kg) + 2.869  1.28 MJ/day
    For females aged 18- 29 years old the equation is.
    BMR (MJ/day) = 0.062(KG) + 2.036 1 1.00MJ/day



















    Limitations

     Lean body mass and brown adipose tissue are not measured which have a strong relationship with metabolic rate.

     Every one has different metabolisms effecting how much of the macro-nutrients will be absorbed. 500 kcal may have been eaten but these values of 500 kcal will have been worked out in a bomb calorimeter and not a human so some of the calories may not be absorbed.

     The medium the protein, carbohydrate and fat are carried in effects absorption as sugar mixed in water, i.e. provides more energy and puts on more body fat than sugar eaten by it self.

     One male after 90 minutes metabolic rate increased by 1240 kcal(if the increase happened for 24 hours). This increase is nearly double of the second largest value. This value gave the males and carbohydrate groups means a vastly increased results that without that value some of the significant differences would have given different results. food really effects this individual or the increase or a mistake had been made.

     Some of the protein group did not eat 500 kcal therefore the true increase of protein is not known from the group.

     Gastric emptying from the stomach after protein and fat meals can take up to 4 hours consequently the thermic effect of the food is going to last that long. The study only lasted for 90 minutes.

     Not every had a FMR2, if FMR2 was not present FMR1 was used instead to obtain the results.

     Not every one ate 500kcals of protein, but as protein still had the greatest increase in thermogenesis it does not effect the overall conclusion however though the true results for protein are likely to be higher and therefore give bigger difference.



    Conclusion

     Protein increases the thermogenesis the most out the three macro-nutrients.

     Fat caused the least increase in thermogenesis.

     The greater the BMI the greater the increase in thermogenesis however as BMI increased percentage increase was not significantly different.

     Males had higher a greater degree of thermogenesis than females however males percentage increase was not significantly different.


    What does this mean in respects to you.

    If you have a constant (e.g. 2,000 kcal) amount of calories to eat and trying to loose weight, eat as many of those calories as possible from carbohydrate and protein as possible. This is as they increase thermogenesis more therefore more likely to leave you with in calorie deficit.
    If you want to become obese (sumo wrestler) eat more fat as the body does not oxidise fat as much as the other two nutrients therefore allowing more fatty acids to be deposited into your adipose tissue.



    Reference

    Kirksey, b., haff,. (1999) busting out of the zone. Musclar development. 36:3, 88

    Stock , m .,Rothwell n (1982)obesity and leanness. John Libbey :London pp51


    Bibliography

    1) Colgan, M. (1993) optimum sports nutrition. Advanced research press

    2) Garrow, J,S.,James, W,P,T. (1996) Human nutrition and dietetics 9th edition.
    Churchill livinigstone

    3) Muscular development magazine(1998-200) various articles through out different editions

    4) Newsholme, E,A.,Leech A.R.((1995) biochemistry for the medical science. John Wilson & sons. Chichester

    5)Rees, D,G.(1995)essential statistics 3rd edition. Chapman and hall

    6) Stock , m .,Rothwell n (1982) obesity and leanness. John Libbey :London

  2. #2
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    this was done in our nutrition lecture so not all the relavent data is there as i do not need to tell make lecturer all th info as he was particapting in the study etc

  3. #3
    Senior Member Wizard's Avatar
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    I agree that in order to loose weight you have to consume as many calories as possible from carbohydrate and protein,as mentioned BUT in order to loose weight healthy you have to include no less than 20%of daily cals from good fat sources(olive oil,flaxseed oil,sesame oil).
    Either:
    [list=1][*]Your testosterone levels will drop.Hormones' levels affect lean body mass and can increase the BMR. [*]Fat-soluble vitamins A,D,E,K won't be delivered to your body thus causing several problems to your health.[*]Digestion will become too defficult.[*]The absorption rate of carbohydrates will be faster without fats. [/list=1]
    I wrote down just a few.However if you want to loose weight you don't consume the same calories as your maintainance level is and only from protein and carbs while keeping fats too low.You just cut back 300-500 but retain a good ratio of Carbs/Proteins/Fats.Fats can make you fat if your caloric intake is higher than the maintenence levels.
    Also the thermogenic effect of carbs is caused only from complex carbs.You write "carbohydrate" generally while simple carbs have less thermogenic effects than fats.(anyway it's too low for both).
    Last edited by Wizard; 05-01-2001 at 08:06 AM.

  4. #4
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    black - the carbs source was a mix of strawberry jam and white bread - no butter.

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