There's no doubt that exercising in sufficient quantities will affect weight.
Yet in study after study after study, long term exercise in quantities between 150 and 300 minutes per week, while sufficient to slow weight gain, was insufficient to stop it. Know too, those 150-300 minutes a week weren't simple strolls either, but rather were exercise bouts of moderate intensity or more.
And even if those 150 or more minutes did actually lead to a real impact upon weight, would it be a realistic expectation that they' be doable? In my own life I just barely hit those 150 minutes a week. By way of example, two good weeks are posted below. The first week includes 3 forty-five minute weight lifting sessions and 1 thirty minute run (165 minutes).
In short, I'm incredibly fortunate and incredibly privileged (and incredibly thankful), and while surely I could have exercised more, I couldn't have done so without that more becoming negative.
That said, there are those who can and do enjoy more. And of those great exercisers, some are filled to the brim with self-righteous sanctimony and assert that because they themselves are capable of exercising in large enough quantities to impact their weights, so too could everyone else. But those people, undoubtedly, don't work with the general public on lifestyle change. Because if they did work with the general public they would understand that for most people, real-life challenges, concerns, and responsibilities often understandably trump finding 3.5 or more hours a week to enjoy moderate or greater intensity exercise. Whether it's caregiver responsibilities, co-existing medical illnesses, mental health concerns, severe financial strain, holding down multiple jobs, chronic pain, chronic child or parental mental or physical health problems - these issues and more, definitely, fairly, and rightly challenge the luxury of enjoying large quantities of intentional exercise.
My exercise mantra remains the same. Some is good. More is Better. Everything counts. And the good news too is that lesser amounts of exercise, while unlikely to have a dramatic impact upon your weight, may well have a dramatic impact upon your health, mood, sleep, and quality of life, all the while preserving your functional independence as you age.
We need to consciously stop tying exercise to weight as its lack of affect therein and/or the incredibly large amounts required to affect it, might well lead a person to give up, or never start exercising, yet exercise, at any weight, might as well be magic when it comes to health.
Some is good. More is better. Everything counts.