And that's exactly what researchers did.
In a study published in the journal Obesity, researchers assessed body composition and behavioural patterns including diet, physical activity and substance use on three islands that varied in their degree of economic development. They then analyzed relationships among their measures. One of the islands was characterized by small rural villages made up of subsistence farmers. The other was also rural but their main economy was tourism. The third was Vanuatu's urban capital city.
Researchers asked questions about: Ancestry, family history of NCDs, occupation, education, subsistence related activities, 24 hour dietary recall, frequency of sports and sedentary behaviours and substance use. The researchers measured: BMI, body fat percentage (both by means of bioimpedance analysis and multiple skin folds), waist circumference, and waist to hip ratio.
The findings weren't all that surprising, yet still are worth reviewing. Risk of obesity, increased body fat percentage, increase waist circumferences and waist to hip ratios all went up in lock step with degree of economic development.
And the biggest predictor of weight change? Processed food consumption - in this case tinned fish canned in oil or sauce served with instant noodles or rice (versus the more traditional fresh fish with root crops and vegetables).
As would be expected, physical activity and sedentary behaviour had much weaker associations with weight change than did diet.
Unfortunately convenience foods aren't particularly convenient for health.