Childhood obesity and consumption of fizzy drinks: Diet is not that important in obesity
BMJ 2004; 329 doi: https://doi.org/10.1136/bmj.329.7456.54 (Published 01 July 2004) Cite this as: BMJ 2004;329:54
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As a perennial and avid non-exerciser for, oh, 30 years and during
this time retaining a medium, non-obese build, I would provide a dueling
anecdote to the good doctor.
I recall reading a US Yearbook of Agriculture article published
sometime in the 1940's and having to do with how to fatten penned pigs --
important to the farmer because of being paid per pound. The article
related that high protein and high saturated fat kept these pigs lean,
even without exercise. What porked them out was carbohydrate (e.g. corn)
and polyunsaturated fats, just the things I believe that increase the
propensity of humans to become overweight. Polyunsaturated fats, as
products of the seed oil industry and therefore novel, in an evolutionary
sense, to our diet, are not only carcinogenic and immunosuppressive (they
can be used to prevent transplant rejection) they also(from a physiologist
friend of mine)reduce metabolic rate by apparently inhibiting the
proteases responsible for converting T4 to T3, the active form of thyroid
hormone. Maybe they do or maybe not, but they do make pigs fat by some
mechanism. And the amount of such fats has been increasing in our diets
for decades, from virtually zero 100 years ago to a substantial portion of
our caloric intake today.
As for exercise, I suspect Dr. Spence is somewhat of an ideologue
because of what he fails to say, namely the morbidity, if you will, of
exercise. He's not alone, of course. Several years ago in the US it was
reported that 8 high schooler died in that year alone, and that was only
from injuries sustained just from high school football. The report didn't
mention, spinal cord injuries, joint sprains, broken bones, eye damage,
repetitive concussions...there's a long list. Psychologists debate
endlessly over the downsides of organized (by adults) compulsory
competitive sporting events for children for the lessons they teach. And
why subject any child to their loony, hysterical parents on the sidelines.
Other than obeying the Common Law, I am opposed to compulsory or
forbidden anything since I don't like to ram my ideas down other people's
throats nor do I want others to do that to me (so go ahead and eat
polyunsaturated fats if you want to; I avoid them,along with exercise, but
I might be wrong). There's a lot of wisdom in the bumper sticker: "Eat
right, exercise regularly, and still die."
Competing interests:
None declared
Competing interests: No competing interests
This article unbelievably states “Childhood obesity is not caused by
diet but by a lack of exercise pure and simple.” No doubt exercise is
extremely important and can attenuate, to some degree, the effect of junk
food on weight gain, but it is ridiculous to say that childhood obesity is
not caused by diet.
This report un-scientifically uses anecdotal evidence to suggest this
connection. Are there any studies comparing energy consumption of children
from present day to that of the 1970’s??
While obesity has numerous influences, generally obesity is a
disorder of excess intake of energy relative to energy expenditure.
Children do not become obese through lack of exercise alone, they come
obese due to excess intakes of total energy, fats, and high glycemic load
meals, genetic influences on metabolism (e.g. fat oxidation, leptin
levels, relative BMR) and lack of exercise. The influence of exercise on
energy balance is less than that of diet. If children where not eating
such bad diets, the majority would not become obese despite a lack of
exercise.
Regards, Blake Graham, BSc (nutrition) student
Competing interests:
None declared
Competing interests: No competing interests
From anecdotes to evidence
While anecdotes provide light relief, the evidence on causes of
obesity is clear (less so, the evidence on treatment and prevention).
National dietary surveys in the UK show a decrease in total energy,
percentage energy from total fat and per capita sugar consumption since
the 1970s to the present day. Some argue that under-reporting of food
intake has skewed these results but they are the best we have at the
moment.
National surveys of activity show that we are expending less energy
through work, travel and leisure time. That fits with the mechanised, car-
oriented, sedentary leisure-loving society that we all recognise.
Epidemiology has linked high energy dense diets and high fat diets to
obesity. In reality, high fat diets tend to be more energy dense than low
fat diets. Interestingly, high sugar diets are correlated with a lower BMI
than low sugar diets.
Evidence from studies of overweight people shows that, while they
have a higher total energy expenditure (because of their larger body
mass), they engage less in physical activity. This doesn't tell us much
about what they did before gaining weight. However, work on 'at risk'
children, i.e. those with one or more overweight parent, suggests that
they are less active outwith school, watch more TV and sleep longer.
The bottom line is that lack of physical activity is probably the
main causative factor in the obesity epidemic. However, I do think high
energy density diets contribute and can hamper treatment and prevention
unless physical activity is routinely vigorous.
Competing interests:
Dr Ruxton is also a freelance nutritionist working with a range of food and weight management companies.
Competing interests: No competing interests