Weight loss ultimately comes back to the concept of calories in, calories out: Eat less than you burn and you’ll lose weight. And while it’s possible to lose water weight quickly on a low-carb diet, I certainly wouldn’t advocate for it. The diet itself can trick you into thinking that this eating style is working — when really, you might gain back what you lost as soon as you eat carbs again. That can feel incredibly dispiriting if you want results that last longer than a week.
Don't get me wrong — exercising at any time is good for you. But evening activity may be particularly beneficial because many people's metabolism slows down toward the end of the day. Thirty minutes of aerobic activity before dinner increases your metabolic rate and may keep it elevated for another two or three hours, even after you've stopped moving. Plus, it'll help you relax post-meal so you won't be tempted by stress-induced grazing that can rack up calories.