Hardly anyone loses weight and keeps it off (80% fail rate within a year) regardless or what avenue they take.
There’s a decent correlation between the exercise and weight loss, but not causation. That correlation may be from any number of factors:
Nutrition is Key in Weight Loss
Nutrition is “dominant” in cases of Weight Loss (regardless of Success or Failure). Activity is “incidental” and “associated” but but saying it is “important” (significant) to Weight Loss specifically is an overstatement.
Basically, it’s a correlation vs causation argument when discussing exercise. Whereas we can actually prove causation with nutrition. This is not to say that Activity “does / does not cause Weight Loss” only that “we do not know the level to which Activity causes Weight Loss (over time)” whereas “we have a high confidence in the level of which Nutrition causes Weight Loss (over time).”
I Couldn’t Outrun My Fork
My weight has gone up and down over the years, and when I’ve wanted to lose weight its always been precipitated by exercise. Then again, I started training in Thai Boxing in my teens and trained with pro fighters that would regularly train for 4-8 hours a day. So I learned a strong work ethic when it comes to exercise. This is obviously way beyond what most people would ever do or be capable, especially those needing to lose lots of weight.
Professional Athletes Can Outrun a Bad Diet
However, this idea that ‘you can’t outrun a bad diet’ and things is ridiculous in the context of professional athletes because you absolutely can. And almost all professional athletes do so on a regular basis. Sure they are expending tons of energy, but this is the point. They expend so much energy that it is nearly impossible to eat more in a single day than would be required for them to put on tons of weight and actually become overweight.
The Adage is just that. It applies to MOST people. Keep in mind PROFESSIONAL athletes are not only outliers but also in peak physical condition usual at the peak age. They can figuratively eat anything because their bodies treat it all like rocket fuel. Their TDEE is off the charts are incomparable to most of us. Hell, when I’m in “competitive” (for me) Marathon season, I can eat whatever I “want” without worrying about weight gain… but three days after MCM I have to cut the intake or I’ll baloon up. But no one ever got fat on one meal or skinny from skipping one.
Exercise Has Lots of Other Benefits
Exercise is amazingly important and has LOTS of benefits. It absolutely does. Weight loss is not one of them.
Exercise can Help:
Weight Control (it helps TDEE)
Exercise is a Pillar of Physical Fitness, but nutrition is far more important than activity when it comes to Weight Loss, and unfortunately many (if not most) people don’t start activity proactively. They start it reactively which means that they must look at the cause (Nutrition) first.
Consult a Dietitian
I think our perception of how much we do or don’t know about nutrition is heavily influenced by popular media. Articles and news segments about nutrition are very popular because nutrition is a field the general population feels like they can relate to and understand. You don’t see many news segments or articles circulating the general public concerning the latest findings in Neuroscience or Radiology because most people would not know what they are talking about. But with nutrition, it’s easy to understand vitamins and things that we put into our mouths.
As of results, we hear and see about many latest findings on BuzzFeed or whatever, and the influx of new information happening so constantly convinces us that the field is constantly changing and not much is certain.
You may have a very different opinion about nutrition if you speak to a couple of experience dietitian about what they find important and what they see is the most recent developments in the field.