Plant-based eating tends to be higher in carbs and lower in protein than an omnivorous diet, but protein and iron deficiency are rare—even among steadfast vegans. (Vitamin B12 deficiency is more of a concern, so strict vegans should consider taking a supplement.) Cutting back on animal foods will remove most of the cholesterol and saturated fat from your diet, but that does not necessarily make your diet low in fat.
Though our culture has become much more vegetarian- and vegan-friendly than it used to be, your choices will still be limited at fast-food restaurants, highway rest stops, and Grandma's—which can work in your favor in that you may cut down on extraneous calories.
Once you know where to look, however, you'll find plenty of overprocessed vegan junk food. If you're serious about losing weight and upgrading your health, you'll want to focus on whole, unprocessed foods and steer clear of added sugar, salt, and fat—just like everyone else!