This spring, it’s likely there will be a new diet pill on the market. Belviq (lorcaserin) won approval from the FDA last spring, making it the first weight-loss drug approved in 13 years, and the DEA proposed this week that the drug be classified as a Schedule IV controlled substance.

Perhaps most importantly, Aetna recently decided to provide coverage of the drug made by Arena Pharmaceuticals.

BLOG:Does Childhood Obesity Affect Brain Development?

So how does it work?

WATCH VIDEO: Why Do We Feel Thirsty?

Belviq is an appetite suppressant. The new chemical entity works by activating the brain’s response to serotonin. Serotonin is a neuro-transmitter known for evoking happy moods; some anti-depressants work by keeping serotonin levels elevated. Belviq works specifically with the serotonin receptors involved with appetite, according to Time.

In trial, patients who took Belviq lost 3 to 3.7 percent more weight than those taking a placebo; after taking it for one or two years, 47 percent lost at least 5 percent of their body weight (compared to 23 percent of those who took a placebo), WebMD reports.

Another new weight loss drug, Qsymia, is already on the market, although sales have been slow.

PHOTOS: Could Air Pollution Be Making Us Fat?

Belviq is approved for obese people and overweight people who have another weight-related disease or risk factor. Side effects include headache, dizziness, fatigue, nausea, dry mouth and constipation; in patients with diabetes, additional side effects include low blood sugar, back pain, and coughing.

No excuse to skip the gym, however: the drug only works in conjunction with exercise and a balanced diet.

Photo: Arena Pharmaceuticals Inc/Handout