The fact that weight loss is 20% exercise and 80% diet gets thrown around a lot, and while those of us that have put in our time might understand it, it might not be immediately obvious to some.
For weight loss, while ultimately it's the quality of the food that's important, it mostly boils down to calories in vs. calories out. You need to create a calorie deficit. You can go about that in 3 ways: eat less, exercise more, or both.
If you're not paying attention to what you're eating, and limiting it to a reasonable, healthy level, it's very easy to undo any exercise you do by eating too much.
An intense round of exercise could easily burn around 600 calories in an hour. But you could eat a Big Mac in about 5 minutes and BAM, there goes 590 calories.
Workout all you want, but you just cannot out-train a bad diet.
Along with the how much you eat, you also need to be cognisant of what you're eating. 100 calorie snack packs of Doritos does not a healthy snack make. Yes, it might be easy to just grab a premixed "meal replacement" shake for breakfast, but it's also probably filled with preservatives and other crap your body just doesn't need.
If you want to get the most out of your workouts, you need to eat real, whole foods, being sure to get a balance of complex carbs, lean proteins and good fats.
Lastly, while weight loss may be mostly about what you eat, fat loss is about a combination of diet and exercise. Weight loss without strength/resistance training is a combination of fat loss and muscle loss, and losing muscle is generally not a good idea. Exercise is also important for general health.
I'm not a doctor, a nurse, a strength coach or a dietician, so in no way is my word final, but I've been living the life and reading a lot over the last few years, and I've seen what works, and what works for good. Crash dieting is one (stupid) thing, but losing fat for life is entirely different.
If anyone has any questions, we've got a lot of really knowledgeable people here on the board, so just ask. There's no magic pill that will make you skinny, but the way to becoming healthy isn't a mystery, it just takes effort!
We'll just not tell H about this little fact, m'kay?
