To prove a point once, I lost a few kg while eating a diet that consisted solely of pizza.<p>Upon saying that, I wouldn't recommend it. The best weight management methods are holistic, the different facets of healthy weight management: exercise, meal composition, and serving size, all play into each other.<p>You want to exercise more, eat less, and eat healthier.<p>If you eat healthier; whole grains instead of refined carbs, lots of leafy greens, legumes to replace carbs, and avoid processed foods; then you'll feel satiated while eating less, both in calories and in just bulk amount of food.<p>You'll have more energy from a diet consisting of whole foods instead of refined carbs, which will allow you to exercise more and exercise harder. There's no reason why you can't burn 800 calories in an hour of hard exercise with the right diet and motivation. It might be different for other people, but for me, exercising also makes me want to eat healthier.<p>I've found that group classes (crossfit, spin, etc.) are a great motivator to exercise too. If you see the same people every time you go, you form a group and it becomes a social activity. Obviously that's not for all of us, but I always struggled with motivation to go to the gym solo. When I started doing functional fitness group sessions, I couldn't stop. I went to every session (3 times a week) for 8 months, the only sessions I missed were when I was out of town. Otherwise I'd turn up no matter how I felt, whether tired, sick, or hungover, I'd drag my arse out.<p>The big thing is really motivation. Going solo, it's really easy to lose motivation. If you have friends who are also eating healthy and working out with you, it really helps. For me, it was other people in my coworking space. The space was really big into healthy lifestyles, so there were a bunch of us who would bring healthy food to work and go to the gym together. Another great tip is to avoid buying any packaged food. Only eat food you've prepared yourself, that way you don't accidentally eat a bunch of food you don't need to as you need to physically go out of your way to make food to eat. That may include cutting bread out of your diet, it's too easy to make a piece of toast if you're peckish, it's a lot more work to cook a potato.<p>I didn't lose as much weight as I wanted to because alcohol was a major food group, but I toned up a whole lot and felt a lot healthier in general. It also had a positive mental health effect.<p>Unfortunately I moved overseas and lost my momentum. It's been 8 months since I've gone to a gym and I've managed to pick up most of my old bad habits again. At least I can still run 5 km (3 miles) in 30 minutes, so it's not all gone.<p>Anyway, my point is: technically, yes, simply counting calories will work for weight loss. But that's the hard way. You'll feel like shit, constantly hunger and lacking energy. Take a holistic approach to your health. And if you don't exercise and eat healthy food, you might get skinny, but you'll still be unfit and unhealthy, you just won't get a heart attack at 30.