The level of physical activity of Kitavans was roughly estimated at 1.7
multiples of the basal metabolic rate (BMR) [1]. BMR multiples for
westerners with low occupational activity level who are non-active at
leisure time is 1.4 for both sexes, while moderately active persons at work
as well as during leisure time is 1.7 for males and 1.6 for females [2].
For 18-30 year old Kitavan males the estimated energy expenditure was 9.4
MJ, while their estimated total daily calorie intake from diet history was
9.2 MJ. Energy expenditure decreased with aged in both populations. In the
Swedish population self reported physical activity during work and leisure
time were each coded to a three-point scale (low, medium and high level of
physical activity) using a questionnaire [3].

Men spend their time gardening, relaxing, fishing, building houses, carving
and playing football (soccer), while women most of the time are weaving,
cooking, gardening, relaxing or washing clothes. The two single most common
activies are gardening and sitting still. The annual variation of physical
activity is considerable, particularly for men. It seems to decrease
slightly with age in both sexes. Individual levels of physical activity
were not assessed.

Although the precision in the calculated energy expenditure is low, it is
obvious that Malinowski's statement that "half of the natives' working life
is spent in the garden" [5] will falsely suggest that Kitavan life is
filled with hardship. On the other hand, if "working life" means time for
production of food, clothing and houses, Malinowski's figure seems accurate.

The given figure of estimated energy expenditure is too uncertain to admit
any strict comparison with other traditional populations or with westerners
[6]. Nevertheless, by modern western standards, the annual mean level of
physical activity appears high, although a considerable proportion of
western labourers evidently work more strenuously and have less time for
leisure activities. Furthermore, the leisure activities of many westerners
are quite heavy and time-consuming.

In conclusion, the mean level of physical activity was higher in Kitava
than in Sweden, although overlapping between the two populations appears
considerable (which it was not for leanness). Although the higher level of
physical activity may explain some of the beneficial health status of
Kitavans, diet appears even more important. Unfortunately this is not much
more than a guess because our survey methods preclude any detailed
judgement.

A fairly low level of physical activity has been the rule among many
traditional populations, particularly hunter-gatherers and tribal
horticulturalists, who have spent an average of three hours or less each
day on food production [7-10]. On the one extreme, a female Machiguenga of
the Amazon dug up enough tubers in one hour to feed 25 adults for one day
[11]. On the other extreme we find populations living in deserts, the
Arctic or similar marginal habitats and who have spent more than seven
hours a day hunting or gathering  [7]. The very high level of physical
exercise exerted by the Tarahumara Mayans of Mexico [12] can hardly be
considered representative for traditional human populations. Loren may
however not agree on this last one [13].

Physical activity undoubtedly exerts a number of potentially beneficial
effects on cardiovascular risk factors, including reduction of blood
pressure, body weight and waist to hip ratio, and elevation of HDL-C [14].
Higher levels of physical activity are furthermore prospectively associated
with lower mortality [15, 16]. Besides its possible genuine effects,
exercise may facilitate an adequate intake of essential nutrients by way of
increased energy expenditure [17]. Nevertheless, available evidence do not
suggest that exercise is as efficient as dietary changes to lower body
weight [14] or blood pressure [18] and exercise alone is apparently
insufficient to fully prevent insulin resistance [4]. My personal
impression from cross-cultural surveys is not that a high level of physical
activity is a necessary condition for very low rates of IHD.

As for fitness, this is very difficult to evaluate. Does fitness give
health or does health give fitness?

Best wishes, Staffan


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activity predicts high activity of tissue plasminogen activator: the
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Press, 1981: 344-421.
8.      Sahlins M. Stone Age Economics.Chicago: Aldine, 1972
9.      Taylor CB, Ho KJ. Studies on the Masai. Am J Clin Nutr 1971; 24:
1291-3.
10.     Lee RB. What hunters do for a living, or, how to make out on scarce
resources. In: Lee RB, DeVore I, ed.  Man the hunter.  Chicago: Aldine,
1968: 30-48.
11.     Johnson A, Behrens CA. Nutritional criterioa in Machiguenga food
production decisions: a linear-programming analysis. Human Ecology 1982;
10: 167-89.
12.     Groom D. Cardiovascular observations on Tarahumara Indian
runners--the modern Spartans. Am Heart J 1971; 81: 304-14.
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factor. Am Heart J 1991; 122: 1723-39.
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ischaemic heart disease in middle-aged British men [published erratum
appears in Br Heart J 1992 Feb;67(2):209]. Br Heart J 1991; 66: 384-94.
16.     Sandvik L, Erikssen J, Thaulow E, Erikssen G, Mundal R, Rodahl K.
Physical fitness as a predictor of mortality among healthy, middle-aged
Norwegian men [see comments]. N Engl J Med 1993; 328: 533-7.
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At 12:36 -0700 98-05-11, Art De Vany wrote:
>Staffan Lindeberg made this very interesting point:
>
>"However, contemporary Trobriand Islanders in Kitava are very lean and
>obesity is absent despite a carbohydrate intake which is higher than in
>Western populations (approximately 70 per cent of calories). There
>is food
>in abundance and no starvation. Low serum insulin levels (extremely well
>predicted from their body mass index) which decrease with age suggest
>rarity or absence of insulin resistance (Lindeberg et al, submitted).
>
>Possibly, the quality rather than the quantity of carbohydrates is
>important; carbohydrate-rich foods with a low glycemic index and a high
>nutrient density (per energy unit), such as Kitavan tubers and fruit, may
>be preferable to cereals and sugar (and potatoes?)."
>
>I wonder if Staffan could indicate something of the nature of the
>physical activties, and their patterns over the season and by age,
>of these islanders.  Surely, their fitness would be a factor so
>that, even with a very high CHO intake, they might retain their
>insulin sensitivity.  Is it not also true that insulin resistance
>increases as body fat accumulates, particularly in the abdominal
>area?  Might not the leanness of these peoples be a factor?  If they
>are active, have adequate lean body mass, and (therefore) retain
>insulin sensitivity, then perhaps the Trobriand Islanders Paradox
>can be explained.  The quality of the food may also be a
>contributing factor, as this assures a good lean body mass among all
>ages.