It's a proposition some might find hard to swallow: a 20-percent tax on unhealthy food to improve the health of the nation.

Yet such a tax — spread across the food chain from manufacturer to consumer, coupled with changes in food policy to spur production of healthier food — is needed to reverse the pandemic of obesity and chronic diseases, researchers say.

Two articles published online today (May 15) in the British Medical Journal describe this course of action. These opinion pieces come one week before the 65th World Health Assembly, to convene on May 21 to 26 in Geneva, where diet-related diseases will be the primary topic.

Size of fat tax

One article, led by Oliver Mytton of Oxford University's Department of Public Health, looked at tax schemes worldwide to see what has worked, however marginally. Many countries are now using such "sin" taxes, which have curbed tobacco and alcohol use, to limit the consumption of unhealthy food, Mytton said. These taxes are based on the basic economic theory that, as the price of an item rises, the consumption of that item will fall. [7 Diet Tricks That Really Work]

But this theory isn't necessarily true with food, Mytton said. Just because the price of microwave-ready, deep-fried, gooey cheese sticks goes up doesn't mean the nation will switch to kale. People might continue eating deep-fried, gooey cheese sticks, because that's what they like to eat and that's all they know how to eat.

Mytton's group, however, found numerous cases in which a relatively high tax altered food consumption in a healthful way. One example comes from Denmark, where early assessment is showing that a new relatively high "fat tax" on oh-so-cherished saturated fat has prompted people to eat foods with a healthier fat profile. Another study comes from Boston, at the Brigham and Women's Hospital cafeteria, where a 35-percent increase in the price of sugary drinks led to a 26-percent reduction in consumption.

Analyzing such food tax schemes, Mytton's group eyeballed a 20-percent tax as the level at which changes on food consumption become noticeable.

Mytton is cognizant of unintended consequences of food taxes — for example, trading one evil for another, less sugar for more fat, or buying less healthy food for lack of money to buy any food. For this reason, he suggests introducing a sugary beverage tax, in which the alternative is usually drinking more tap water.

"A tax isn't going to fix obesity; it's not going to fix diet-related diseases," Mytton said. "There's no single solution. But it can have a role in moving people in the right direction" with their eating patterns. Mytton also would like to see subsidies for healthy foods, such as fruit and vegetables.

Here is the definition of "Nanny State" This is what liberals want. Families? Nope. Government? Yeap.