It was sort of beautiful in its simplicity, but I can see why this hasn’t caught on.

From Diets and Data by Emily Oster.  She is referencing a useful research paper recently published.  

It starts by noting the key underlying principle of weight loss: energy deficit. You need to burn more calories than you take in to lose weight. Period. As the paper says more formally: The key component of diets for weight loss and weight-loss maintenance is an energy deficit. Under the “calories-in, calories out” model, dietary management has focused on the concept of “eat less, move more.”  

The link between weight loss, calories consumed, and exercise is a little more complex, since as you lose weight your baseline energy expenditure adjusts. But the principle of needing an energy deficit remains true. And if you want to generate this energy deficit through food, you need to eat fewer calories.  

I liked her observation.

The simplest diet, then, is just … eat less. This is best epitomized by a good book I once read called The Economists’ Diet. The primary message was that to lose weight you need to weigh yourself every day and eat less. And, also, that you’ll be hungry a lot of the time. It was sort of beautiful in its simplicity, but I can see why this hasn’t caught on.

Hers is a good summary.  For all the fads and billions of dollars, weight is a choice.

The paper concludes with two thoughts: 

Reducing daily calorie intake is the most important factor for weight loss.

The best diet for weight management is one that can be maintained in the long term.

There is no best diet. Or, no single best diet. The best diet for any purpose is one you can stick to. This extends beyond weight loss. Changing your diet for better diabetes management, or better cholesterol management, or blood pressure — all of these require being able to stick to it. If you are going to change how you eat, it’s crucial to do so in a way that is sustainable. 

This matches my personal experience.  Ten or fifteen years ago I had a bad accident, requiring major surgery on my left leg.  I was bed bound for many weeks and inactive for several months.  My energy expenditure was down dramatically but I failed to adjust my intake.  Across some six months I added perhaps twenty pounds to an already present excess of ten or fifteen pounds.  

In the subsequent decade, I put an occasional dent in that surfeit of 35 pounds, but never for long.  The usual litany of excuses - much travel, irregular meals, wining and dining clients and project teams, long hours of work with little structured or consistent exercise, etc.  

Making things somewhat more legitimately difficult over the past fifteen years has been collapsing foot arches exacerbated by increasing pronation of ankles, all on top of reasonably severe rheumatoid arthritis.  It was actually increasingly difficult to walk much less exercise without kicking the whole system out of balance and causing major joint flair-ups.

In the past fifteen months, given the enforced isolation and business disruption arising from policies to address Covid, I took the opportunity to have reconstructive surgery done on each foot in sequence.  Each surgery was followed by a similar-to-last-time cycle of being bed bound and then very constrained ambulatory movement for months.  The unexpected aspect was that rebuilding the arches and eliminating the pronation affected the entire skeletal structure as everything readjusted back in to place but with especial impact on the knees.

Going into this, and given my prior leg surgery experience, I recognized that my only avenue of weight control was to reduce intake.  I would have a year or two of very constrained opportunity for exercise.  

Dispensing with types of diets, I simply reduced intake with an awareness of maintaining some form of dietary balance (protein, vitamins, roughage, meat/vegetables/fruit, etc.)

And it worked.  Lost twenty pounds in the first nine months.  Fifteen to go.  Once I am fully ambulatory again, I anticipate the final fifteen to be easier to address.  Possibly a foolish anticipation.

Once I am back at some sort of normal target weight then maintenance is the key.  Possibly difficult once travel and social interaction resumes, but hopefully not.  

It all came down to choosing to reduce intake and drinking more water.  Exercise has not been an option and won't be for another three months.