You have to make a lifestyle change. If you eat shit, and you sit there like a pile of shit, you will look like a pile of shit, and you will feel like a pile of shit.
We are mammals, and we aren't supposed to sit inside all day. We need to move around and get some sun, or our biological systems are going to continue to store fat like it's winter. Without Vitamin D and exposure to fresh air instead of the toxic inside environments we work in, including low levels of oxygen due to poor ventilation, we have trouble getting all of our biological systems to run like they are supposed to.
I am in a constant battle with my weight, which I am usually on the losing side of. When I cut out all sugar, including sugar in coffee, and I focus on eating vegetables and non-meat sources of protein, I feel like absolute hell for three days and then I feel amazing until I start eating crap again. This time around I'm going kind of nuts with pressed kale/apple/carrot juices and very little meat. The change is astounding. Within a week all of the weird aches and pains I had, including some of my back pain, began to disappear. (I am down to a BMI of 30 from 36, and still trending down).
I really think the Western diet starves us of basic building blocks for repairing and maintaining our bodies, and as we discover more about our symbiotic relationship with bacteria, I bet they will find out that the ingestion of products (sugar, processed flour, etc) that easily turn into glucose make our symbiotic bacteria go apeshit and stop serving their purpose. It's like stuffing petri dishes into your body and hosting a microbiological world war.
The funny thing is that once I rid my tongue of the expectation of a wall of salt and fat and sugar, healthy foods that seemed bland are suddenly rich with flavors and it's no problem snacking on carrots and raw broccoli with hummus or whatever and staying away from sugar drinks which are now overly sweet. I can get an Americano with a touch of milk and it tastes like chocolate if the beans are good. Roasted whole vegetables (which I am trying to learn how to cook myself) are as satisfying as any fast food meal, but I don't feel like shit an hour later.
Probably the best side affect is that my body now tells me when it's full. Two years ago I could eat an entire pizza without really thinking about it. Now I can have a bowl full of vegetables and feel more satisfied. (Not sure what the science behind that is, exactly, but it works.)
Mass produced foods are designed to addict, and kicking that addiction is just as important as kicking a smoking habit, if not more. Once I hit my target BMI, if I can stay on track, I will introduce a small amount of meat back into my diet, but I'm fairly convinced that processed sugar and processed wheat are literally poison for our mammalian biological systems. Now that it's out of mine, I don't have to think about going outside. Getting up and moving around is no longer a chore. It's actually becoming a joy that I haven't felt since I was a kid and spent every possible moment outside.
Anyway, tl:dr; Pollan seems to be right. Eat lots of veggies, a little bit of dairy, and a tinier bit of meat. Drink water. Go outside. Do not drink sodas or eat fast food, ever. If you put garbage in your body, your body will turn into garbage.