ah perfect topic to answer
There is so much myth in this industry and misinformation could write a book about that but there are too many lol.
You do not *NEED* excessive exercise - Too much of g a good thing is not good. To lose weight you need to consume less calories than your total energy expenditure. In simple terms, excess consumption causes the body to store as fat. The problem here, is that not everyone is created equal, many factors will determine how much you can eat or not eat, depending on your metabolic rate. Some people can eat ridiculously high amounts and remain skinny (me when I was in my childhood years LOL) and you have those who barely eat and gain weight (hormonal issues, health issues, medication, etc.).
We all are burning energy even doing nothing (resting metabolic rate) - exercising helps you burn more than your base metabolic rate and lose weight faster than doing nothing, however, there is a big catch. If you exercise excessively and you create a calorie deficit too big, over time your body will adjust and down regulate your metabolism and you will stall ! This is why crash diets fail and people who starve themselves and exercise can actually have all kinds of other issues, messed up hormones, etc.
It is simple, eat more than you energy requirement = you gain weight.
Eat less than your calories requirement = lose weight
If the amount of calories you eat equals your daily maintenance = you don't lose / don't gain.
But there is another catch, not all calories are created equal - you also have to take into account that digestion uses up calories too
So reasonable exercise, proper nutrition, change in life styles, being active whilst NOT over exerting yourself, and making sure not to create too big of a deficit... Those 500-800 kcal diets won't cut it, try not to create a deficit higher than 25% of your maintenance - SLOW weight loss = weight loss you normally keep. FAST and unsafe weight loss = you will likely gain quickly and more. Don't give your body a chance to down regulate too much. Slow and steady for long term results.
Then comes the TYPE of foods you eat. If you are eating foods high in carbs, you can do all the exercising you want, you will mostly burn glycogen - remember your body wants to get rid of sugar first, fat last, so in priority it is depleting your glycogen store first (and most of it is stored in your liver), the rest in your muscles. Some people do low carbs to lose weight fast, as your body gets adapted to burn fat (Ketosis state) but this is not required either, you can still lose weight on a diet with the proper balance of fat, protein, carbs. Some exercise favour burning glycogen stores and others are using more fat storage - so the TYPE of foods you eat and TYPE of exercise is important.
If you exercise heavily and eat 3 whole bread sticks that will be counterproductive lol.
If you cut your calories and carbs too much your leptin levels tank, and that too is counter productive. Too much of the wrong exercise = increase in cortisol level (the stress hormone) which is not good.
A balance of the right exercise and right foods goes a long way.
GRADUAL changes is best. Making drastic cuts = bad.
If you consume 5 bread sticks + 6 packs daily, try to cut something, say, 3 cans of soda instead and 2 bread sticks, then gradually replace the unhealthy foods you eat with alternative, healthier food.
Those who are on a high carb diet and make some small changes will notice the most great results.
Also another thing - there is no miracle to FAT LOSS........ LOSING WEIGHT is one thing, LOSING FAT is another, it is a long process - if you exercise heavily, and go on the scale it will register a number few pounds lower, you did not lose weight you lost water and it's associated glycogen you burned off. To lose actual weight you need to burn around 3500 calories - and you won't be doing that in one session at the gym and if you do, I don't recommend it, lol.
High carbers or diabetics will have a harder time losing weight due to the medication and high insulin levels - people who are insulin resistant also will have a harder time.
Remember everything in moderation - that includes exercise.