More complicated than that, you have obese who look normal and overweight people in perfect shape. Metabolic syndrome is linked to insulin resistance, big stomach is one symptoms but fatty liver and visceral fat are not te same than subcutaneous fat.
To fix it : no more high glycemic index food, les carbs and , no more seed oil (linoleic acid).
Processed food love to use sugar as it is addictive and cheap and seed oils are cheap and tasteless.
It's difficult to advice olive oil in Thailand but palm oil, coconut oil or ghee are better.
Obesity code by Jason fung s a must read on the subject they should translate it in Thai.