Any pointers on how to break out of a plateau?

Is it actually possible to NOT lose
weight because you're eating too little?

Yes and no. This gets a little complicated so let me explain both sides.

Part one of my answer: I say NO, because if you are in a calorie deficit you
WILL lose weight.

Most people have heard anecdotes of the dieter who claims to be eating
800 calories a day or some starvation diet level of intake that is clearly in
a deficit and yet is not losing fat. Like the mythical unicorn, such an animal
does not exist.

Every time you take a person like that and put them in a hospital research
center or metabolic ward where their food can be counted, weighed, measured
and almost literally "spoon fed" to them, a calorie deficit always produces weight loss.

There are no exceptions, except possibly in rare diseases or mutations. Even
then metabolic or hormonal defects or diseases merely lead to energy imbalance
via increases in appetite, decreases in energy expenditure or changes in energy
partitioning. So at the end of the day it's STILL calories in versus calories out.

In other words, NO - it's NOT your thyroid (unless you've got a confirmed
diagnosis as such...and then guess what... it's STILL calories in vs calories out,
you're just not burning as many as someone should at your height and weight).

One famous study that was published in the New England Journal of Medicine
years ago proved this point rather dramatically. After studying obese people -
selected specifically because they swore they were eating less than 1200 calories
but could not lose weight - Steven Lichtman and his colleages at St. Luke's
Roosevent Hospital in New York came to the following conclusion:

"The failure of some obese subjects to lose weight while eating a diet they
report as low in calories is due to an energy intake substantially higher than
reported and an overestimation of physical activity, not to an abnormality
in thermogenesis."

That's right - the so-called "diet-resistant" subjects were eating more than they
thought and moving less than they thought. This was probably the single best
study ever published that debunks the "I'm in a calorie deficit but I can't lose
weight" myth:

Part two of my answer, YES, because:

1) Energy intake increases.

Eating too little causes major increases in appetite. With hunger raging out of
control, you lose your deficit by overeating. This happens in many ways, such
as giving in to cravings, binge eating, eating more on weekends or simply being
inconsistent, so some days you're on your prescribed 1600 calories a day or
whatever is your target amount, but on others you're taking in 2200, 2500,
3000 etc and you don't realize it or remember it. The overeating days wipe
out the deficit days.

2) Metabolism decreases due to smaller body mass.

Any time at all when you're losing weight, your metabolism is slowly decreasing
due to your reduced body mass. The smaller and lighter you get, especially if
there's a large drop in skeletal muscle mass, the fewer calories you need. So
your calorie deficit slowly shrinks over time as your diet progresses. As a result,
your progress slows down even though you haven't changed how much you eat.

With starvation, you always lose weight, but eventually you lose so much
weight/body mass that you can reach energy balance at the same caloric
intake you used to lose weight on. You might translate that as "I went into
starvation mode" which wouldn't be incorrect, but it would be more accurate
to say that your calorie needs decreased.

3) Metabolism decreases due to adaptive thermogenesis.

Eating too little also causes a starvation response (adaptive thermogenesis) where
metabolic rate can decrease above and beyond what can be accounted for from
the change in body mass (#2 above). This is "starvation response" in the truest
sense. It does exist and it is well documented. However, the latest research says
that the vast majority of the decrease in metabolism comes from reduced body
mass. The adaptive component of the reduced metabolic rate is fairly small,
perhaps 10% (ie, 220 calories for an average female with a 2200 TDEE). The
result is when you don't eat enough, your actual weight loss is less than
predicted on paper, but weight loss doesn't stop completely.

There is a BIG myth about starvation mode (adaptive thermogenesis) that
implies that if you don't eat enough, your metabolism will slow down so much
that you stop losing weight. That can't happen, it only appears that way
because weight loss stops for other reasons. What happens is the math
equation changes!

Energy balance is dynamic, so your weight loss slows down and eventually stops
over time if you fail to adjust your calories and activity levels in real time each
week.

So what can be done to stop this metabolic slowdown caused by low calorie
dieting and the dreaded fat loss plateau that follows? I recommend the
following 5 tips:

1) Lose the pounds slowly.

Slow and steady wins in long term fat loss and maintenance every time. Rapid
weight loss correlates strongly with weight relapse and loss of lean body mass.
Aim for one to two pounds per week, or no more than 1% of total body weight
(ie, 3 lbs per week if you weigh 300 lbs).

2) Use a higher energy flux program.

If you are physically capable of exercise, then use weight training AND cardio
to increase your calorie expenditure, so you can still have a calorie deficit, but
at a higher food intake (also known as a "high energy flux" program, or as we
like to say in Burn The Fat, "eat more, burn more.")

3) Use a conservative calorie deficit.

You must have a calorie deficit to lose fat, but your best bet is to keep the
deficit small. This helps you avoid triggering the starvation response, which
includes the increased appetite and potential to binge that comes along with
starvation diets. I recommend a 20% deficit below your maintenance calories
(TDEE), a 30% deficit at most for those with high body fat.

4) Refeed.

Increase your calories (re-feed) for a full day periodically (once a week or so if
you are heavy, twice a week if you are already lean), to restimulate metabolism.
On the higher calorie day, take your calories to maintenance or even 10, 15, 20%
above maintenance and add the extra calories in the form of carbs (carb cycling).
The leaner you get, and the longer you've been on reduced calories, the more
important the re-feeds will be.

5) Take periodic diet breaks.

Take 1 week off your calorie restricted diet approximately every 12 weeks or so.
During this period, take your calories back up to maintenance, but continue to
eat healthy, "clean" foods. Alternately, go into a muscle building phase if increasing
lean mass is one of your goals. This will bring metabolism and regulatory
hormones back up to normal and keep lean body mass stable.

Train hard and expect success,

Tom Venuto,
Author of Burn The Fat, Feed The Muscle
http://www.BurnTheFat.com