Stay Active - Eat Like a Champion

Canadian Nutrition Month 2009 Theme

Mar 16, 2009 Alicia Richardson

Experts say regular physical activity is the key to a healthy weight - not caloric restriction

To maintain heart health at peak levels, Health Canada and the Institute of Medicine recommends that children and adults spend up to at least one hour daily in moderate activity such as walking, playing golf, swimming, dancing, gardening, etc. Walking briskly, running, jogging, fast cycling, aerobics, playing competitive sports e.g. hockey, football, etc. are examples of intense physical activities.

Because carbohydrates, fats, and proteins can be used as fuel by the body, it is recommended that adults get 45%-65% of their total energy requirements from carbohydrates, 20%-35% from fat, and 10%-35% from protein. Infants and very young children's nutritional needs are similar to adults except they need more fat - about 25% to 40%, This is because their bodies burn more fat than adults.

It is important to balance physical activity with total caloric intake. Total caloric requirements varies from person to person depending on age, height, weight, gender, level of physical activity, and medical condition (chronic or acute illness).

For example, a 30 year-old 5'5" sedentary woman weighing 111 to 150 pounds can consume 1,800 to 2,000 calories a day. If she becomes moderately active (exercises for one hour, 5-7 days per week), she can consume 2,000 to 2,500 calories. With intense exercise, she can consume 2,500 to 2,800 calories.

Health benefits from regular exercise is cumulative. Sedentary persons can begin an exercise program by walking 4 miles per hour for 60 minutes everyday and gradually working at a higher intensity workout like jogging for 20-30 minutes 4-7 days a week. for weight loss.

How the Body Uses Energy

The human body spends energy through: basal metabolism, physical activity, thermic effect of food (specific dynamic activity of food or SDA), and adaptive thermogenesis.

About two-thirds of people's energy expenditure goes into basal metabolism- involuntary activities that support life such as respiration/breathing, blood circulation, repair of tissues, etc. Children, pregnant women, and the physically fit and have lean muscle mass (elite athletes) have the highest basal metabolic rate (BMR).

Fever, stress, heat/humidity, nicotine, and caffeine increases BMR. Taller people have higher BMRs because they have greater skin surfaces.

In contrast, advancing age, fasting, starvation, malnutrition, and those with more body fat than muscle, have lower BMRs. BMR is lowest during sleep. Thyroxin (a hormone) can either increase or decrease BMR.

Physical Activity can increase or decrease energy expenditure. Because it is variable, it is key to weight loss or weight gain. Muscles burn more energy than fat tissues. The larger the muscle mass, the larger the energy expenditure. Also longer, more frequent, and intense physical activities results in greater energy outputs.

Comprising of about 10% of energy intakes ,the thermic effect of foodis the energy needed to digest, absorb, transport, metabolize and store ingested nutrients. Carbohydrate foods have a higher thermic effect than fatty foods.

Adaptive Thermogenesis can increase energy expenditure in times of extreme stress such as severe cold, trauma, etc. This is due to the extra work demanded by the body . It is not included when calculating energy needs.

Of the four energy output routes, physical activity is the most accessible means of modulating weight

and caloric intake.

References

"Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids National Academy of Sciences, 2005; pp:107-264; 265-338;422-541;589-768
Health Canada Website
Dietitians of Canada Website

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