Vegan diets CAN be among the most healthy diet types if you are following a "whole food plant-based" diet.
You can learn more about that here, here, here, here, and here if you want specifics.
But in a nutshell, healthy vegan diets are typically generally focused on consuming whole unprocessed plant-based foods. That also means no added salt, no added sugars, and no added oils or fats. (Which also means the diet prohibits the use of cooking oil).
Celebrity Las Vegas magician Penn Jillette tells his story following a similar diet and how he lost enormous amounts of weight with no exercise here.
I tried following a diet that was generally whole food plant-based for a few months and I found I was losing about 10 pounds a month with no exercise, and also noticed I was feeling very energetic and about 6-10 years younger. This continued until I dropped down to a weight level close to what I was at in high school or early college. And that was even while I was occasionally cheating on the diet.
the diet that has the most scientific evidence to support it for sustained weight loss is a high-card low fat vegan diet. here's an excellent book called How Not to Diet by Dr. Michael McGreggor. Dr McGreggor reviews all published research on nutrition each year and makes videos discussing the research, available for free through his website NutritionFacts.org. The book he published contains just shy of 5,000 references to peer-reviewed research and it analyzes and discusses the scientific evidence relating to nutrition, dieting, weight loss and how to keep it off. well worth the read.
The How Not to Diet Cookbook: 100+ Recipes for Healthy, Permanent Weight Loss https://www.amazon.com/dp/1250199255/ref=cm_sw_r_cp_api_glt_fabc_WKV02NDXHZGJ024X7VWX
I'm currently working my way through the How Not To Diet Cookbook and How Not To Die Cookbook and my entire week's meal plan came from them.
We always have oatmeal with flaxseed and fruit for breakfast, then for every day, I picked a meal salad for lunch, a hot dish for dinner, and a dessert.
For this week the recipes are:
Mon
Summer Salad - How Not To Diet pg 36
Root Vegetable Mac & Cheese - How Not To Diet pg 86
Mango Raspberry Chia Cup - How Not To Diet pg 194
Tue
Indonesian Gado-Gado Salad - How Not To Diet pg 66
Penne Primavera - How Not To Diet pg 75
Strawberry Banana Nice Cream - How Not To Die pg 370
Wed
Southwest Kale Salad - How Not To Diet pg 46
Gemelli with Zucchini Meatballs - How Not To Diet pg 83
Black Forrest Chia Cup - How Not To Diet pg 196
Thu
Chopped Salad Bowl - How Not To Diet pg 61
Stuffed Bell Peppers - How Not To Diet pg 114
Fudge Brownies - How Not To Die pg 373
Fri
Christmas at relative's house (no cooking)
Sat
Corn and Black-Eyed Pea Salad - How Not To Diet pg 49
Roasted Root Vegetables - How Not To Diet pg 99
Baked Apples with Walnuts - How Not To Diet pg 199
Sun
Barley Tabbouli Salad - How Not To Diet pg 51
Cummin Roasted Carrots - How Not To Diet pg 117
Berry Chocolate Chia Cups - How Not To Die pg 376
I normally don't plan my menus like this with all new recipes. But I recently got these cookbooks and I've been having a lot of fun going through all the recipes. They're all very well received by my family too, which matters a lot because my husband has split custody over his teen kids and they eat meat when they're at their mom's house (and aren't super keen on eating vegan when they're here). So hitting a cookbook where they'll gladly eat anything I make out of it without whining is a rather big deal for us. lol
We eat Whole Food Plant Based 90% of the time, so look for those kinds of recipes/cookbooks.
I actually use cookbooks very rarely, but it just so happens that I'm currently working my way through the How Not To Diet Cookbook and How Not To Die Cookbook. Which I both like a lot.