There is a “widespread misimpression” that weight-loss and maintenance for bodies which have become and stayed obese for more than a couple of years, is essentially the same as that for bodies which always have been:

• normal weight (BMI between 18.5-24.9);
• overweight (BMI between 25-29.9); or
  
• have spent a brief time within Grade 1 obesity (BMI between 30-34.9).
  
  

In a commentary published February 26, 2015 in the journal Lancet Diabetes and Endocrinology, four weight-loss specialists set out to correct what they view as the widespread misimpression that people who have become and stayed obese for more than a couple of years can, by diet and exercise alone, return to a normal, healthy weight and stay that way.

"Once obesity is established, however, body weight seems to become biologically 'stamped in' and defended," wrote Mt. Sinai Hospital weight management expert Christopher N. Ochner and colleagues from the medical faculties of the University of Colorado, Northwestern University and the University of Pennsylvania.  

“Few individuals ever truly recover from obesity.” Those that do "still have 'obesity in remission,' and are biologically very different from individuals of the same age, sex and body weight who never had obesity." They are constantly at war with their bodies' efforts to return to their highest sustained weight.

That February 2015 commentary together with the August 2013 research article below explain many of the things that I have experienced personally, and that I have personally observed.

An additional article dealing with this issue is located HERE in the DietHobby Archives.

Biological Mechanisms that Promote Weight Regain Following Weight Loss in Obese Humans
          by Christopher N. Ochner; Dulce M. Barrios; Clement D. Lee; F. Xavier Pi-Sunyer
                     Published August 2013

Abstract

Weight loss dieting remains the treatment of choice for the vast majority of obese individuals, despite the limited long-term success of ...

We all have choices on how we are going to live our lives, and where we are going to place our focus.  My choice may not resemble your choice. I am a “reduced obese” person who has maintained a “normal” weight for more than 9 years, after a lifetime of Yo You Dieting. See ABOUT ME for details.

Doing this has required my constant vigilance, ongoing effort, and tremendous focus, and even though I have been more successful than 95% of everyone who has ever accomplished a large weight-loss, it is been a tremendous personal struggle, and year-after-year, despite CONSISTENT and CONSTANT effort, my weight has continued to slowly creep upward in small increments over time.

This is despite the fact that the recorded daily calorie average of my food intake has been dropping lower and lower each year.

For example, at the start of 2015, my weight was the same as it was at the start of 2014, however, the average daily calories of all of my daily food intake during the year of 2014 was only 754 calories.

In 2013, the average daily calories of all of my daily food intake was 1033. So my average daily food intake was about 280 daily calories LESS than the prior year, and during that prior year, from the start of 2013 until the start of 2014, my body gained 8 pounds while eating that 1033 calories per day.

These are my personal facts, based on numbers which I recorded as accurately as humanly possible, every single day for the past 10 years. For years I felt like Garfield in the cartoon below, but now... instead of yelling "Liar" at the scale, I mentally yell "Liar" or "You Idiot" at the 'Diet Experts' who smugly believe the B.S. and provide to us the results of bad Research, while asserting that "Science Doesn't Lie".

NOTE: that I am a 5’0” tall, 70 year old, sedentary woman with a lower than average metabolism, and according to the Mifflin formula, the AVERAGE woman with my numbers requires only 1237 daily calories to maintain her current weight.

I give you this information so you can see that my recorded calorie numbers are not as far out in left field as some of you might first suppose. You can’t accurately compare my body’s numbers with your own body’s personal calorie calculation requirements if you are larger, taller, younger, more active etc. ...

The fat burning process is a complex biochemical process.

When you “lose” body fat, the fat cell (also called an adipocyte) does not go anywhere or “move into the muscle cell to be burned”. The fat cell itself, (unfortunately) stays right where it was – under the skin in your thighs, stomach, hips, arms, etc., and on top of the muscles – which is why you can’t see muscle “definition” when your body fat is high.

Fat is stored inside the fat cell in the form of triaglycerol. The fat is not burned right there in the fat cell, it must be liberated from the fat cell through somewhat complex hormonal/enzymatic pathways. When stimulated to do so, the fat cell simply releases its contents (triaglycerol) into the bloodstream as free fatty acids (FFA’s), and they are transported through the blood to the tissues where the energy is needed.

A typical young male adult stores about 60,000 to 100,000 calories of energy in body fat cells. What triggers the release of all these stored fatty acids from the fat cell? When your body needs energy because you’re consuming fewer calories than you are burning (an energy deficit), then your body releases hormones and enzymes that signal your fat cells to release your fat reserves instead of keeping them in storage.

For stored fat to be liberated from the fat cell, hydrolysis (lipolysis or fat breakdown), splits the molecule of triaglycerol into glycerol and three fatty acids. An important enzyme called hormone sensitive lipase (HSL) is the catalyst for this reaction. The stored fat (energy) gets released into the bloodstream as FFA’s and they are shuttled off to the muscles where the energy is needed. As blood flow increases to the active muscles, more FFA’s are delivered to the muscles that need them.

An important enzyme called lipoprotein lipase (LPL), then helps the FFA’s get inside the mitochondria of the muscle cell, where the FFA’s can be burned for energy. If you’ve ever taken a biology class, then you’ve probably heard of the mitochondria. This is the “cellular powerhouse” where energy production takes place and this is where the FFA’s go to be burned for energy.

When the FFA’s are released from the fat cell, the fat cell shrinks and that’s why you look leaner when you lose body fat – because the fat cell is now smaller. A small or “empty” fat cell is what you’re after ...

"Approximately two-thirds of people who lose weight will regain it within 1 year, and almost all of them will regain it within 5 years.

Although dieting (ie, caloric restriction) to lose weight is a difficult task, the maintenance of lost weight requires the patient to deploy even greater efforts.

Rather than a simple lack of willpower, the relapse of most individuals to their previous weight after otherwise successful weight loss is largely driven by the coordinated actions of metabolic, neuroendocrine, autonomic, and behavioural changes that oppose the maintenance of reduced body weight.

The few individuals successful at maintaining weight loss (at least 13.6 kg (30 lbs) for at least 1 year) generally have common behaviour and strategies that include consuming low-energy, low-fat diets; engaging in high levels of physical activity; consistent self-monitoring of body weight and food intake; eating breakfast regularly; and demonstrating a high level of dietary restraint.

It is highly unlikely that some of this behaviour can be emulated by most of the population with excess weight.

There is also concern that unhealthy weight control methods (eg, fasting, meal skipping, laxatives, diuretics, stimulants) might ultimately lead to a larger weight regain and pose a risk to both mental and physical health.

Thus, although sustained weight loss with diet alone can be possible for some individuals, agreeing on realistic weight-loss expectations and sustainable behavioural changes is critical to avoid disappointment and nonadherence.

Weight regain (relapse) should not be framed as failure but as an expected consequence of dealing with a chronic and complex condition like obesity."

This has been true for me personally.  See my previous article:  Running DOWN the UP Escalator.

The above article involves a paper about the Widespread Misconceptions About Obesity published in Canadian Family Medicine in November 2014 written by obesity experts - Dr. Sharma et al, and it was originally posted originally posted at his website - Dr. Sharma’s Obesity Notes.