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Some Dietary Issues in Exercise:
Weight Control
Maintaining adequate nutritional status is not
much of a problem for healthy & active
individuals who eat reasonably well . . .
Things are different, however, when restricting
calories . . .
With the Estimated Energy Requirement (DRI) for Adolescents & Adults being so
much higher than the caloric intake necessary to get the minimum nutrients . . .
Males
(9 yrs – 13 yrs
~ 2250)
14 yrs – 18 yrs
~ 3150
19 yrs – 50 yrs
~ 3050
- subtract 10 kCal / day for each year over 19 yrs
Females
(9 yrs – 13 yrs
~ 2100)
14 yrs – 18 yrs
~ 2350
19 yrs – 50 yrs
~ 2400
- subtract 7 kCal / day for each year over 19 yrs
Remember This Healthy Diet Concept:
Number of Food Servings for Daily Caloric Intakes:
Food Group
Standard
Serving Size
Approximate
Calories /
Serving
~ 2000
kcal
~ 2200
kcal
~ 2500
kcal
~ 2800
kcal
Fruits
0.5 cup
71
5
5
5
5
Vegetables
0.5 cup
38
6
6
6
6
Cold-Water Fish
4 ounces
120
2/wk
2/wk
2/wk
2/wk
(Lean Meats on
3 ounces
remaining days are optional)
120
-
-
-
-
Nuts & Seeds
0.25 cup
240
1
1
1
1
Beans & Legumes
0.5 cup
110
2
3
3
3
Dairy
1.0 cup/2 oz.
86
3
3
3
3
Breads & Cereals
1 slice/1 oz
78
5
6
7
7
Red Wine
4 oz
85
1
1
1
1
110
2
2
3
3
Added Fats
1 Tbsp (EVOO)
Discretionary Calories
200
*1900/2000 kCal intake meets RDA requirements on average; 2200 kCal or more meets or exceeds
requirements each day. . . So it just shouldn’t be so difficult
400
Adapted from: Nutrition for Sport and Exercise, Dunford & Doyle, 2008
Unfortunately . . . the average non-restricted American diet really sucks . . . especially
in the area of fruits and vegetables; major sources of many vitamins and minerals . . .
Resulting in an almost non-existent probability
of being adequate . . . especially with a calorierestricted diet!!!
Adapted from Nutrition for Sport and Exercise, Dunford & Doyle, 2008
Because we really really like to go on weight loss-loss diets . . . And lose
weight as fast as possible . . . It is not unusual for us eat 1,000 or 1,200 kCals
each day while trying . . . Vitamins and minerals are already a “lost cause”,
but even the minimum requirements for the major macronutrients (CHO, AA,
FFA) can be at risk . . .
AI
130 g/day
45% to 65% of total calories (4 kcal/g)
IOM recommends 1 hour of moderately stressful exercise
every day
NRG for moderately stressful exercise is 50 – 80%
carbohydrate . . .
6 – 7 mph ~ 600 – 800 kcals
@ ~50% ~ 300 – 400 kcals = ~ 75 – 100g additional CHO
Therefore, a logical minimum DRI would be more than the
IOM recommendation
~ 200g/day would be a reasonable estimate
AI
0.8 g/kg; 1.0 - 1.4 g/kg with exercise
10% to 35% calories (4 kcal/g)
Nitrogen balance studies indicate that more is needed with exercise
...
. . . labeled infusion studies on the use of amino acids for synthesis
and metabolism indicate a decrease in proteolysis / with a
maintenance of synthesis following repeated exercise; leading to a
reduction in the dietary protein requirement . . . Therefore the IOM
recommendation for 1.2 – 1.4 g/kg with moderate to stressful
exercise may be somewhat dubious
&
Because average American consumes > 2X DRI already, modifying
dietary content of protein also is of dubious benefit…
AI
12 & 17 g/day linoleic acid (C18:2; n6, 9 - all cis): F / M; based on on median intake
1.1 & 1.6 g/day α-linolenic acid (C18:3; n9, 12, 15 - all cis) F / M; based on median intake
Or: 10 - 35% of total calories (9kcal/g)…
so… lets see what you have to eat to…
Some older texts suggested a minimum total intake of 20g/day to insure a sufficient uptake of fat
soluble vitamins which greatly underestimates the actual dietary lipid requirement (RDAs are based
on fatty acid intake, not TG intake and eating exactly 12g linoleic acid or 1.1 g α-linolenic acid would
obviously necessitate eating more than 13g total fat since the EFA are a small minority of total FFAs)
EFA Content of various foods in % of total FA
Canola Oil
Corn Oil
Olive Oil
Palm Oil
Peanut Oil
Flax Oil
Beef (grain-fed-trimmed)
Beef (grass-fed-trimmed)
Chicken (skinless-breast)
Salmon (Norway-wild)
Linoleic
~ 26
~ 35 - 65
~ 3 - 20%
~ 6 - 12
~ 14 - 43
~ 14
~ 3.4
~ 4.4
~ 21
~1
α-Linolenic
% Fat by Wt
100
100
~ 1%
100
~ 0.5
100
~ 0.4
100
~ 50 - 60
100
~ 0.4
~5
~ 1.2
~ 2.5
~ 0.9
~ 4.5
~ 1 (2%EPA/20% DHA) ~ 3 - 4
Human Milk
Cow Milk Fat
~7 - 18
~ 2.6
~1
~ 1.6
~2-4
~ 0, 1, 2, or ~3.5
Based on the EFA content of common foods (as a percent of total fatty acids) you clearly have to eat
a lot more grams of fat than the RDA (as expressed in grams for the EFA’s) – 60 g/day would not be
an outlandish minimum estimate.
Summary
Minimum Macronutrient Intakes:
Carbohydrate: ~ 200g/d
Protein:
~ 0.8 g/kg/d (~60 g?)
Lipid:
~ 60 g/d
Total kCal
=
=
=
=
800 kCal
240 kCal
540 kCal
1580
At 1900 kCal (following the recommended servings):
carbohydrate =
protein
=
lipid
=
~ 250g (55%)
~ 70g (16%)
~ 60g (30%)
Recommended %
(IOM)
45% - 65%
12% - 20%
20% - 35%
At 1200 kCal (cutting the recommended servings to exactly 63%):
carbohydrate
protein
lipid
~ 157g
~ 44g
~ 37g
At this intake, protein is below the minimum AI for a
sedentary person . . . And carbohydrate is below the minimum
recommended for an active person . . . And fat is below a
“reasonable minimum”…
Obviously, the “average” American who attempts a weight-loss diet will be
deficient in something in a very short time - especially if they go on one of those
fad diets that severely restrict one of the major macronutrients; such as the
Atkin’s diet.
The best solution is to first revise the diet to be consistent with the
recommended array of servings:
See recommended servings for. . . And then introduce physical activity (500
kCal minimum) . . . And then monitor weight and skinfolds . . . And then figure
out what to do; adjust servings (trial & error) . . .
Number of Food Servings for Different Daily Caloric Intakes
________________________________________________________________________________________________________________
Standard
Average
*Required
Recommended
Serving
kcal/
Food Group
Size
Serving
~1900 kcal
~2200 kcal
~ 2500 kcal
~ 2800 kcal
________________________________________________________________________________________________________________
# Servings
____________________________________________________
Fruits
0.5 c.
71
4
4
5
6
Vegetables
dark green
deep yellow
starchy
other
0.5 c.
0.5 c.
0.5 c.
0.5 c.
20
38
76
18
2
1
1
2
2
1
1
3
3
2
1
3
3
2
2
3
Meat/Fish/Eggs
3 oz.
165
0
1
1
1
110
240
2
1
3
1
3
1
3
1
Beans/Legumes
Nuts/Seeds
0.5 c.
0.33 c./0.25 c.
Dairy (skim/low-fat)
milk/yogurt
cheese
1 c.
~ 2 oz.
86
3
3
3
3
Breads/Cereals
(whole grain/fortified)
0.5 c.
1 slice
78
5
6
7
9
Added Fats
1 Tbsp.
100
2
2
2
3
*Red Wine
4 oz.
85
1
1
1
2
________________________________________________________________________________________________________________
The ~1900 kcal recommendation follows the minimum required number of servings from each food category as described in the Optimal Health
Guide. Caloric values are based on the tabled values for nutrient and caloric content of food servings available in the 2005 IOM and USDA
recommendations. These values are based on averaged values from mixed food servings from the North American diet and should be
considered to be reasonable estimates.
*Can safely be removed from the minimum without compromising nutrient intake to produce a ~ 1800 kcal intake.
Calories Burned For 30 Minutes Exercise*
________________________________________________________________________________________________________
Exercise
Approximate
Calories Burned for the Indicated Body Weight
Intensity
________________________________________________________________________________________________________
110 lbs
150 lbs
190 lbs
_____________________________________________
Bicycling
Hard (fastest possible)
Moderate (~ 10 mph)
Easy (~ 5 mph)
255
165
90
350
225
120
445
285
152
Running
10 mph
8 mph
6 mph
415
350
265
565
475
360
715
600
455
Weight Lifting
Hard
Moderate
175
130
240
175
305
225
Stationary Rowing
Hard
Moderate
270
180
370
245
465
310
Aerobics
Hard
Moderate
205
165
280
225
350
285
Swimming
Hard
Easy
550
165
750
225
950
285
Basketball
Moderate
150
205
260
Golf
Carrying
Cart
130
110
180
150
225
190
Rollerblading
Hard
Moderate
270
235
370
320
465
400
Walking
4.5 mph
170
235
295
3.5 mph
125
175
220
2.5 mph
95
130
165
________________________________________________________________________________________________________
*Please note that these caloric-expenditure values are approximate only. Everyone is different and some people may burn as much
as 15% fewer than these values or 15% more than these values and the value amount will change with training & diet.
Be absolutely “anal” about counting & measuring servings and tracking
your minutes of exercise activities every day.
After a few weeks you will have a good idea about your estimated
average calorie intake and your estimated average exercise calorie
output.
Try moving toward the minimum-servings diet plan… as long as you stay
near the minimum servings/day (w/o wine) your intake will be around
1800 kcal/day and developing a nutritional deficiency will be minimized.
See what happens…
Adjust exercise minutes and/or servings every couple weeks to see what
happens & to produce a weight-loss of no more than 2 pounds/week there should be no hurry!
Too Much - Too Fast!
2000 kcal/day Caloric Deficit
Week
Body Mass
% Body Fat
Total Fat
Fat Loss
Lean Loss
0
162
18%
29.16 lbs
-
-
1
158
17%
26.86
2.30 lbs
1.70 lbs
2
154
15%
23.10
3.76 lbs
0.24 lbs
3
150
14%
21.00
2.10 lbs
1.90 lbs
Total Fat & Muscle Loss
Total Fat Loss
Total Lean Mass Loss
~ 12 lbs
~ 8 lbs
~ 4 lbs
~ 4 lbs/week
NOT really a good thing - Lose 8 lbs fat in 3 weeks and lose 4 lbs
of indispensable tissue along with it!!
1000 kcal/day Caloric Deficit
Week
Body Mass
% Body Fat
Total Fat
0
161
18%
28.80 lbs
-
-
1
159
17%
27.03 lbs
1.77 lbs
0.23 lbs
2
157
16%
25.12 lbs
1.91 lbs
0.09 lbs
3
155
15%
23.25 lbs
1.87 lbs
0.13 lbs
4
153
14%
21.42 lbs
1.83 lbs
0.17 lbs
Total Fat & Muscle Loss
Total Fat Loss
Total Lean Mass Loss
~ 8 lbs
~ 7.4 lbs
~ 0.6 lbs
Fat Loss
Lean Loss
~ 2 lbs/week
A much better result - Lose 7.4 lbs fat over 4 weeks
and only 0.6 lbs of the good stuff
Some Dietary Issues in Exercise:
Negative Calorie Balance
(Eating Disorders and Disordered Eating)
Throwing stressful exercise into the mix seems to really screw
things up . . .
The Female Athletic Triad is a good example of how things appear
to be something they are not:
- Disordered eating
- Amenorrhea
- Osteoporosis
Primary (ONLY?) cause is disordered eating
Disordered Eating - Some Data:
- low-energy diet ie. a negative energy balance: anorexia nervosa
(1.3%), bulimia nervosa (8%), anorexia athletica (8.2%, of elite
female athletes in 1993 Norwegian survey); 5.6% AN/NB in
collegiate athletes with ~30% at risk in 2002 survey…
Disordered eating is common in weight-sensitive sports: gymnastics,
light-weight rowing, martial-arts, ballet, distance running, diving, figure
skating …
- eating disorders are usually considered obsessive: AN & BN are
obsessive, disordered eating (AA) is usually not
- chronic caloric deficits force physiological adaptation
- chronic caloric deficits in face of “normal american diet” imply
nutritional deficits as well
- amenorrhea and osteoporisis result from the physiological
adaptations to calorie (& nutrient) deficits
Athletic Triad: presence of Disordered eating + Amenorrhea + Osteoporosis:
- Elite athletes
4.3%
(14 hours stressful exercise / week)
- Active controls
3.4%
(~ 5 hours exercise / week)
Disordered eating + menstrual dysfunction:
- Elite athletes:
26.9%
- Active controls:
13.8%
Disordered eating + low BMD
- Elite athletes:
10.2%
- Active controls:
15.2%
Menstrual dysfunction + low BMD
- Elite athletes:
5.4%
- Active controls:
12.4%
Add it all together and ~ 47% elite and ~ 45% control athletes could have a problem!
Negative Energy Balance & Amenorrhea
Eating insufficient calories leads to amenorrhea
studies document women athletes who are amenorrheic eat the
same or fewer calories each day than non-active women
decreased T3 and Leptin are observed in women with “athleticamenorrhea” and both are directly associated with
negative caloric balance
prolonged negative energy balance leads to decreased GnRH, LH,
and ultimately: ovarian failure, resulting in lower estrogen
levels and higher prolactin levels; both of which lead to
amenorrhea
The endocrine response to negative caloric balance also affects bone cells
Reduced estrogen and enhanced cortisol are major endocrine responses to
starvation that can directly effect bone cell function.
Major bone cells:
Osteoclasts: bone resorption
Osteoblasts: bone deposition
- bone remodeling: a couple weeks of resorption by osteoclasts which
then die through apoptosis
- followed by 3 – 4 months of new deposition by osteoblasts to fill in
the cavity left by the osteocytes and then most die through
apoptosis while some differentiate into osteocytes
- it takes up to a few years for complete re-mineralization of the new
bone.
The endocrine response to negative caloric balance
affects the bone cells
Estrogen normally inhibits osteoclast function to limit the rate of bone
resorption as well as the development of pre-osteoclasts into osteoclasts
Estrogen also decreases local production of IL-6, IL-1, and TNF, all of which
enhance the development of osteoclasts from precursor cells
Therefore:
Reduced estrogen due to starvation greatly enhances bone resorption
(Add in a nutritional deficit from a lousy diet and you then have a real big
problem!!)
Cortisol levels increase as a result of a negative calorie balance in order to
enhance gluconeogenesis . . .
Cortisol also enhances rates of apoptosis in osteoblasts, reducing bone
formation.
Therefore; as a result of low estrogen and high cortisol, both of which
are starvation responses,
osteoporosis will develop . . .
. . . So, lets look at some nutritional aspects of bone formation to see why
osteoporosis is so common . . .
Major Nutrients That Are Important For Bone Formation Include:
Calcium teen
adult
Adult RDA or AI
♂
♀
1300 mg 1000 mg
1000 mg 1000 mg
Median Intake (USA) - NHANESIII
♂
♀
~ 1000*
~ 650
~ 850
~ 600
Phosphorus
700 mg
700 mg
~ 1450
Magnesium 18 – 30 yrs
31 – 50 yrs
400 mg
350 mg
310 mg
265 mg
9+ yrs
~ 310
~ 220
Vitamin D
5 µg
5 µg
Vitamin K
120 µg
90 µg
~ 105
~ 85
Vitamin C
90 mg
75 mg
~ 120
~ 90
Vitamin A
900 µg
700 µg
11 mg
8 mg
Zinc
Copper
Iron
900 µg
8 mg
18 mg
~ 1,000
n/a
~ 1,000RE ~ 800RE
~ 14
~9
~ 1400
~ 1000
~ 17
~ 12
*25+ % prevalence of deficient intake
Major Nutrients That Are Important For Bone Formation include:
Calcium
: component of hydroxyapetite
Phosphorus
: component of hydroxyapatite
Magnesium
: necessary for binding of PTH to receptor & crystallization of matrix
Vitamin D
: 1,25 dOH-D3 (calcitrol): hormone to initiate transcription of Ca++binding proteins
Vitamin K
: necessary co-factor for gamma-glutamyl carboxylase; posttranslational modification for Ca++-binding properties (osteocalcin)
Vitamin C
: necessary co-factor for proline and lysine hydroxylase for
procollagen synthesis
Vitamin A
: RxR binding and osteoclast maturation
Zinc
: a component of alkaline phosphatase that enhances microavailability
of phosphorus for mineralization
Copper
: a component of lysyl oxidase for crosslinking of collagen fibers
Iron
: a component of lysine and proline hydroxylase for stabilization of
procollagen synthesis collagen
Hematopoietic Stem Cells: bone marrow stem cells that can
differentiate into lymphocytes, granulocytes, monocytes,
erythrocytes, osteoclasts . . .
Mesenchymal Stem Cells: bone marrow stem cells that can
differentiate into osteoblasts, chondrocytes, myocytes,
adipocytes. . .
From your extensive knowledge of nutrition stuff (including specific nutrient
sources - that would be individual foods) be prepared to design food intake
resource tables (specific foods, RDA/AIs, and food groups), to illustrate “how
easy” it is to enhance calcium, magnesium, vitamin K, and iron in the diet for
adult female athletes ...
Oh yeah! . . . Include zinc and folic acid as well . . . Just for fun (see next)
And oh yeah again . . . You may want to be the nutritionist and include specific
functions of the nutrients in the same resource tables . . .
Some Dietary Issues in Exercise:
Anemias
Anemias
Iron deficiency can lead to anemia; a reduced volume of RBC’s in the blood
with obvious implications for oxygen-carrying capacity of the blood and
alterations in performance capacity . . . iron deficiency without anemia still
reduces performance
In addition to iron deficiency, anemias also are associated with vitamin B12
deficiency, folic acid deficiency, or extensive RBC hemolysis (can occur with
endurance running)
Iron deficiency
anemia
: microcytic anemia due to inability to
synthesize sufficient hemoglobin
Symptoms include: fatigue / paleness / irritability / tachycardia / pica / sore & swollen tongue
B12 and/or folic acid deficiency
anemia
: macrocytic anemia due to insufficient
DNA synthesis for cell proliferation
during hematopoesis
Symptoms include: nausea / weakness / fatigue / numbness or tingling in hands and feet / decreased
appetite & weight loss / diarrhea / tender tongue – not swollen
Some Major Nutrients That Are Important For RBC Formation Include:
Adult RDA or AI
♂
♀
Median Intake (USA) - NHANESIII
♂
♀
Phosphorus
700 mg
700 mg
~ 1450
~ 1,000
Magnesium 18 – 30 yrs
31 – 50 yrs
400 mg
350 mg
310 mg
265 mg
9+ yrs
~ 310
~ 220
Zinc
11 mg
8 mg
~ 14
~9
Iron
8 mg
18 mg
~ 17
~ 12
Folic Acid
400 µg
unknown / ~ 10%
deficiency in USA
B12
2.4 µg
~ 4.5
Choline
B6
550 mg
425 mg
1.3 mg
~3
unknown
~ 1.9
~ 1.5
*25+ % prevalence of deficient intake
Some Major Nutrients That Are Important For RBC Formation include:
Phosphorus
: essential component of nucleotides
Magnesium
: necessary for (genomic) DNA synthesis and repair - facilitates binding
Cobalamine (B12) : necessary for conversion of methyltetrahydrofolate to tetrahydrofolate
Zinc
: a component of delta-aminolevulinic acid dehydratase for heme synthesis,
zinc-finger motifs of promoters
Iron
: necessary for heme synthesis
Folic Acid
: necessary for thymidylate synthesis (DNA synthesis) & methylation of t-RNA
Choline
: methyl transfer for betaine synthesis in B12/folate cycling for DNA synthesis
B6
: a component of delta-aminolevulinic acid synthase
(Production of Erythrocytes)
In order for high rates of RBC synthesis to be maintained, high rates of
DNA and protein (including hemoglobin) synthesis are necessary . . .
You’ve seen this before . . .
Only now it is labeled with
some nutrient requirements