“He will waste nothing; but he must want nothing,” said theologian John Wesley in a 1772 sermon, inspiring the modern day saying “Waste not, want not.”

We’d like to update the saying even more: “Waist not, want not.”

Researchers who looked at 157,000 postmenopausal women enrolled in the Women's Health Initiative found that normal-weight women with so-called central obesity — that's a fat tummy and a large waist size — risked premature death as much as obese women.

And they were more likely to develop cardiovascular disease and cancer than healthy-weight women without belly fat.

Why is that? Because visceral fat clustered around internal organs is inflammatory, and interferes with organs' normal functioning.

That's why, at any weight, if you have a waist circumference greater than 35 inches (for women) or 39 inches (for men) — measured over your belly button while you suck your tummy in — it's time to start a flat-belly campaign:

• Eat 7 to 9 servings of fruits and vegetables daily. Ditch processed carbs and added sugars or syrups; they're pro-inflammatory foods that increase inflammatory belly fat.

• Work out using resistance bands and hand weights to build lean muscle mass and trigger fat-burning. One study found that 20 minutes of strength-building exercise daily was twice as effective at reducing belly fat as 20 minutes of daily aerobics.

• Eat most of your calories before 3 p.m. and try intermittent fasting.

What you eat and when you eat are equally powerful ways to fight belly fat.