And this many apples.

If you opt for the donuts, you get a lot more calories.

But not all calories are created equal.

Apples contain fiber and vitamins while donuts are full of saturated fats and chemically processed ingredients.

Even though apples are healthier for you, you have to eat more of them to get the same number of calories as one donut.

And it would cost you about five more dollars, which means... the cost-effective choice is usually not the nutritionally-sound one.

There's a strong relationship between diets that are low in fruits and vegetables and obesity and diabetes.

These two chronic diseases now rank among the nation's gravest health concerns.

Produce is essential for a healthy diet, but Americans aren't eating enough of it.

And part of the problem is cost.

So what can be done to add more produce to the American plate?

Fresh fruits and vegetables are often more expensive to farm than other types of crops that end up in processed foods.

For example, fresh strawberries have to be picked by hand.

But strawberries destined for preserves can be harvested by a machine.

Bumps and bruises don't matter in the process, and machines are more efficient and cheaper in the long-run than human labor.

This extra work is reflected in the price difference between fresh strawberries and other crops, and it also makes fresh strawberries more expensive to buy than processed strawberries Government subsidies also play a role in the cost difference.

For example, the USDA doesn't subsidize leafy vegetable crops in the same way it subsidizes wheat, soy, and corn.

These three crops make up a lot of processed food, so products full of high-fructose corn syrup and soybean oil have an unfair advantage.

When it comes to cost, the less nutritious food will win out.

Other incentives are needed to keep people away from cheap, processed foods.

Taxes on tobacco and alcohol have been effective at curbing consumption.

This line shows the average price per pack of cigarettes over the past forty years.

The rising prices are partly fueled by federal and state cigarette tax increases in 1983, throughout the early 2000's, and 2009.

Meanwhile, per capita cigarette consumption shown by this line has steadily decreased as prices have gone up.

And some researchers are arguing that what need to start thinking about a junk food tax.

The tax would focus on non-essential food items like candy, soda and potato chips.

These unhealthy foods would be taxed at the manufacturing level, and higher costs at checkout could steer customers toward healthier options.

But a junk food tax alone won't fix obesity.

Or the already high costs of a healthy diet… So what can be done?

We could make produce sexy.

Okay, well there are other things too.

To address the cost issue, some programs are springing up that make produce more affordable for lower-income people, through subsidies.

And since 2014, the USDA has granted over $65 million to expand these programs throughout the US.

There's also the Fruit and Vegetable Prescription Program or FvRX.

Doctors can give vouchers for produce to low-income patients who are at high-risk of diet-related disease.

Growing produce in home or community gardens can encourage healthy eating with little investment, but finding time to cook, let alone garden, can be a burden for families.

We don't yet know which strategies and programs are work best, but they're worth testing for one simple reason: if Americans ate a wider variety of fruits and vegetables, and more fruits and vegetables, we know they'd be a whole lot healthier.