Recently I visited Portland
Before I offer my answer, let me point out two basic facts. First, on average vegans weigh less than lacto-ovo vegetarians who weigh less (on average) than omnivorous humans. A vegan dietary pattern can protect people from some excess weight gain but it's obvious that many vegans (including raw-foodists) are still overweight. On the other hand, it's fair to presume that these folks are probably a few pounds (if not many) lighter than they would be if they were not vegan.
Second, almost everyone in the US is gaining excess weight. Over two-thirds of US adults are overweight and the entire population weight distribution has shifted drastically over the past 4 decades. This means that even "normal weight" people probably weight 5-10 pounds more than they would had they been born 40 years earlier. Vegans aren't exempt from this phenomenon. We live in a world that makes it easy to eat a lot and hard to expend much energy.
So the main reason why vegans struggle with their weight is the same reason why most people in developed countries are struggling with their weight. (Actually it's a set of reasons which deserve a separate blog or perhaps a book to address)
Let's touch on a few factors that are particularly relevant for vegans:
Vegan Restaurant Portions. If you eat too much healthy food you will gain weight. Vegan restaurants consistently offer mammoth portions. I've eaten at Vegan restaurants in a few dozen cities. One meal typically provides me with enough leftovers for another 1-3 meals. Granted, I am one of those rare cursed folks who has a real hard time eating an enormous volume of food in one sitting. Most people (vegans included) don't have this problem. Think about some of the vegan animals you know (gorillas, elephants, hippos, cows, pigs) and you'll conclude that given ample food any vegan animal can grow enormously large.
Why do vegan restaurants serve so much?! Well, the same reason most restaurants do - economics. Large quantities for little money is considered "good value" by consumers and the cost of the extra portion of food is usually much less than the small additional price increase of the meal. Cheap food means a higher volume of consumers which means more profit. Vegan restaurants often cater to students who are particular sensitive to the value proposition of restaurant meals. And larger portions may broaden the amount of people willing to eat at an all vegan restaurant. Hey Joe Omnivore, want to check out this new vegan restaurant with me? They give you tonnes of food and it doesn't cost much.
Optimistic bias and health halos. Two fun psychological concepts worth understanding. In the context of eating, optimistic bias means you don't think anything bad will happen to you because of your food choices. Other people might gain weight from vegan food, but not me. (This is the same phenomenon that leads most people to think they are not going to die from a heart attack, even when they know that most people do die from heart attacks). We have an intense innate need to feel in control and routinely fool ourselves into believing that is the case. It's hard for us to imagine that a healthy whole foods vegan meal could contribute to weight gain, even in ample quantity.
What's a "health halo"? Here's an example to explain - you see the word "organic" on the front of a cereal box and then throw it in the shopping basket without scrutinizing the nutritional facts or ingredients. The label "vegan" acts as a health halo, magically transforming anything vegan into a healthy food. Vegan smoothie. Healthy! Vegan pizza. Healthy! Vegan donut. Can't be too bad!
In no way am I trying to say you shouldn't be choosing the vegan option. What I'm saying is that all of us are prone to overestimating how good it is for us because it fits a small (albeit valid) list of requirements (no animals killed, organic, etc.). This is particularly true when it comes to calorie content and weight management. We are likely less stringent about portion sizes and calorie monitoring for vegan food then we would be for non-vegan food. And this applies to health conscious vegans too. I do yoga everyday for 2 hours and eat only vegan food. I shouldn't be overweight.
More Options. There are many reasons why a vegan diet causes less weight gain. One simple reason is that it restricts the sheer volume of convenient, readily available calorie heavy food options. At one point this seemed like a bad thing. What do you actually eat? It must be really hard to eat out. My friends used to say this all the time 10 years ago. That's less and less the case, which makes me happy. But in terms of weight management, the more vegan calorie-dense foods available the more vegans will struggle with their weight. Of course, I rejoice at the launch of a new brand of vegan cupcakes, but there is a down side for some.
Basic energy expenditure. We are living in an age of unprecedented calorie-density (e.g. 1200 calorie smoothies) and technological advancement (I have sat unmoving for the past 3 hours only lifting my fingers, but I can honestly claim to be "working"). For most, it's so easy to eat more calories than you use. Adding one hour of exercise a day will make you healthier and happier but it may not fully protect you from weight gain, even on a vegan diet.
A concluding thought.
It is possible for us to create a vegan-friendly world that makes it easier for us all to have a healthy weight. If you are struggling with your weight, adopting a whole-foods vegan diet can be a great step in the right direction. But our work does not stop there.
