chapter
chapter
15
15
Nutrition
and
the
Nutrition
and
the
Active
ActiveFemale
Female
Prof Jennifer Broxterman, RD, MSc
FN3373: Nutrition for Physical Activity
Lecture
10
Author name here for Edited books
Energy and Nutrient
Requirements
Weight Maintenance
• Female athletes must consume enough kcal
to cover energy cost of:
–
–
–
–
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Daily living
Their sport
Muscle tissue growth and repair
Menstruation and reproductive function
Growth (younger females)
Females at Risk
• Female athletes engaged in aesthetic or
lean-build sports with pressure to maintain
lean build or competitive weight
– Dancers, runners, gymnasts, figure skaters
• If weight loss is viewed as a way to improve
performance
Health Consequences of
Chronic Dieting
• Chronic dieting or energy restriction can
lead to:
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–
–
–
Poor energy intake
Poor macro and micro nutrient intake
Decreased resting metabolic rate (RMR)
Decreased total energy expenditure (TEE)
Poor energy and macronutrient intake
• Almost impossible to get adequate nutrients
with energy intake less than 1800 kcal/day
– Protein and carbohydrate intake below RDA
– Fat intake less than 10-15% of energy intake
• Low absorption of fat-soluble vitamins and essential fatty
acids
• Inadequate protein intake for muscle tissue repair
• Inadequate to carbohydrate intake to replenish glycogen
• Fatigue, irritability, decreased performance
Restore Energy Balance
• Increase total daily energy intake (kcal/day)
• Decrease total energy expenditure or add
“rest day”
• Ensure in a state of positive energy balance
before beginning any physical activity
How Do You Know If an Active Female
Is Not Eating Enough?
Poor micronutrient intake
• Micronutrients of concern:
– Calcium and vitamin D: strong bones
• More than 90% of total bone mineral density (BMD) occurs
by 17 years of age, peeks between 25-30 years
– Iron: hemoglobin synthesis, exercise may increase
loss of this mineral
– Magnesium: building and repairing tissue
– Zinc: energy production during exercise
– B vitamins: prevent anemia, necessary for energy
production
Table 15.1
Decreased RMR and TEE
• Severe dieting/energy restriction reduces
RMR
• People who chronically diet have lower total
daily energy expenditure
Energy restriction + High physical activity
fewer kcal required to maintain weight
Strategies to maintain a healthy
weight
• Identify what constitutes a healthy body
weight
– Genetics, physiological, social, sport, psychological
factors
Healthy body weight: weight that can be realistically
maintained, allows for involvement in physical activity,
and reduces risk factors for chronic disease
• Must address changes in lifestyle
Female Athlete Triad
Female Athlete Triad
• Interrelationship between:
– Energy availability
– Menstrual status
– Bone health
• The disorder can arise through:
– Eating disorder (AN, BN, EDNOS)
– Disordered eating tendency
– Inability to eat enough food
• Consequences:
– Amenorrhea & reduced bone mineral density (BMD)
Figure 15.3
Sports at Risk
• Sports that emphasize leanness or a thin body
build may place girls/women at risk:
– Subjective performance scoring: dance, skating, diving,
gymnastics
– Endurance sports: long-distance running, cycling, crosscountry skiing
– Sports involving body-revealing clothing: gymnastics,
swimming, volleyball, aerobics, track, dance, cheerleading
– Weight class sports: horse racing, martial arts,
wrestling, rowing
– Sports emphasizing a preadolescent body build for
success: gymnastics, figure skating, diving
Real Athletes
Real Athletes
Real Athletes
Real Athletes
Real Athletes
Low Energy Availability
• Low energy availability can be caused by:
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Dieting
Disordered eating
Eating disorder
Low energy intake
• Low energy availability is the primary factor
initiating the disorders of the triad
Energy Availability
• Definition:
– Dietary energy intake minus exercise energy
expenditure (EEE)
• Need enough energy for basic physiological
processes:
– cellular maintenance, thermogenesis, immunity,
growth, reproduction, and activities of daily living
Disordered Eating & Eating Disorders
• Eating behaviours form a continuum that
can range from normal to clinically
diagnosed abnormal behaviours
– EDs are diagnosed by meeting criteria outlined by
that American Psychiatric Association’s Diagnostic
and Statistical Manual of Mental Disorders (DSM-IV)
• Anorexia nervosa (AN)
• Bulimia nervosa (BN)
• Eating disorders not otherwise specified (EDNOS)
• It all starts with a diet…
Table 15.2
Anorexia Nervosa
• Diagnostic symptoms:
1. Relentless pursuit of thinness and a
refusal to maintain a body weight at
or above a minimal level.
2. An intense fear of gaining weight or becoming fat.
3. Look at their body differently than healthy individuals
and place a high value on a “thin” body type.
4. Amenorrhea is present due to hypothalamic
dysfunction, which results from malnutrition.
Bulimia Nervosa
• Diagnostic symptoms:
1. There is an uncontrolled desire to overeat or binge
on food. A “binge” is usually determined on an
individual basis.
2. Binge eating must also be characterized by a
subjective sense of loss of control.
3. The binge must occur within a discrete time period.
•
2x/week for 3 months
4. An individual is highly influenced by body shape
and weight in her self-evaluation.
Eating Disorders Not Otherwise Specified
• Triggering factors for EDNOS:
1.
2.
3.
4.
Prolonged periods of dieting.
Frequent weight fluctuations.
A sudden increase in training volume & intensity.
A traumatic stressful event or high levels of stress
(e.g. injury, loss of a coach, stressful family event).
5. Pressure placed on the female to maintain or
achieve a low body weight.
• Sub-clinical eating disorders
Menstrual Dysfunction
• Diet and exercise can negatively effect
reproductive and metabolic hormones
– Amenorrhea
• Starvation-induced
• Exercise-induced
– 3 factors contribute to inadequate energy availability
in active females:
• High energy expenditure
• Low energy intake compared to energy expenditure
• High psychological and physiological stress, which can
reduce energy intake while increasing energy expenditure
Common Types of Menstrual
Dysfunction in Active Women
• Luteal phase defects
• Anovulation
• Oligomenorrhea
• Amenorrhea
– Primary amenorrhea
– Secondary amenorrhea
Factors Contributing to
Menstrual Dysfunction
• Energy deprivation can alter the hormonal
profiles and the menstrual cycle of healthy
women
• Degree of menstrual dysfunction depends on:
– Magnitude of energy restriction
– The body’s level of energy reserves
– Initial hormonal status before dieting begins
• Amenorrhea dietary treatment
Bone Health
• Loss of bone mineral density (BMD):
– Increased risk for osteoporosis
– Increased risk for musculoskeletal injuries (stress #)
• Primary contributors for loss of BMD:
– Low energy intake
– Low bone-building nutrients secondary to malnutrition
Bone Health
• BMD depends on:
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Current age, age when amenorrhea occurred
Length of time an individual has been amenorrheic
Current body size and composition
Type of exercise engaged in
Dietary intakes of bone-building micronutrients
Dietary & drug factors that decrease total body Ca levels
Total energy intake, level of energy availability
Baseline blood cortisol concentrations
Genetics
Stress Fractures
• BMD & stress fractures:
– Positive stimulus of exercise on BMD versus
– Hormonal and dietary changes associated with
menstrual dysfunction = increased risk for #
– Risk of stress # was much higher in athletes with
menstrual dysfunction (52%) than in their
eumenorrheic counterparts (28%)
– Jeopardizes a woman’s athletic career and also
increases her risk for bone # after menopause
Figure 15.5
Warning Signs of the Female Athlete
Triad
Treatment
• Requires a multidisciplinary approach
– Sports medicine team, sport dietitian, psychologist,
exercise physiologist, coach, trainer, parents, friends of
the athlete, and the athlete must work together
• Address level of participation in sport
• Each team should have a standard procedure for
preventing and treating disorders of the female
athlete triad
• Hormone replacement therapy
Treatment: Role of a Sport Dietitian
• Weight:
– discuss weight hx, CBW, desired BW
• Goal of treatment:
– help the athlete be lean, fit, healthy, and develop a (+)
relationship with food
• Anthropometrics:
– baseline body composition measurements
• Address relationship with food
• Estimated nutritional requirements:
– kcal, CHO, protein, fat
Final Exam Update
• Date/Time: Mon. June 23, 2015 @ 1-4pm
• Worth: 35%
• Will be cumulative (greater emphasis on
lectures taught after the midterm)
• Format: multiple choice & some true/false
• Read lecture notes and textbook chapters (to
further your understanding if that helps you
study)