In 2008, actress Kirstie Alley adopted a vegetarian diet for seven months. She said of that time: “I can't tell you how much weight I gained. ... To me, being a vegetarian meant I'm going to eat enchiladas with no meat, and ... lots of bread, lots of carbs.”

In fact, she gained 83 pounds.

Alley’s experience isn't unusual. It's estimated that almost 10% of vegans, around 18% of pesco-vegetarians (they eat fish), and almost 17% of lacto-ovo vegetarians (dairy and eggs) are obese — and even more are overweight.

If you're vegan or vegetarian, it can be a challenge to avoid fried, sugar-added, ultraprocessed, carb-heavy foods.

You also have to make sure you get enough of these two great-for-you nutrients to maintain a healthy weight:

• Protein. Lacto-ovo vegetarians generally hit the recommended daily allowance for protein, but vegans may not.

The Cleveland Clinic says, “substituting protein for carbohydrates ... results in decreased appetite, improved body composition through the maintenance of lean body mass, and a reduction in excess water weight.”

Harvard's Women's Health Watch advises that veggie protein is somewhat different from animal protein. Vegans may need 0.45 grams of protein per pound of body weight per day as opposed to the usual recommendation of 0.4 grams.

Plant sources include legumes, seeds, nuts, soy, and whole grains.

• DHA and EPA omega-3s. Don't eat fish? You're not getting much of these heart-loving, anti-inflammatory nutrients.

Your body converts ALA from plants into EPA and DHA, but not well. So get ALA from flaxseed, walnuts, canola oil, and soy, and take 900 mg of DHA-rich algae oil supplements daily.