The author joined a men's weight-loss group and decided to set
a very different goal from the official one.
He had just read a book on weight loss that recommended clamping
The book says to simply not eat if you don't have a 'good appetite' when the
rest of the family sits down. Have a cup of tea...
down on his habits
until
"
growlies" appeared.
He recognized
This also resembles the way a control system with a thermostat behaves.
No growlies; don't stoke the furnace.
its strategy as
biofeedback
and wanted to see what his body
Possibilities:
The body could gently lower its BMI or
drop too fast (0vershoot) and
bounce back up.
would naturally do if he changed his
habits suddenly.
He plotted the graph
to the right and tinkered with the Rate parameter
until the green line went sideways.
Spreadsheets have a "slope" function, which gave the rate measurement above
(also called a Time Constant measurement).
Sure enough, it turned out to be four seasons.
Secondly, he wanted to see if
Overshoot in a control system usually is caused by a too-fast
response of something in a closed signal path.
"yo-yo" dieting
In yo-yo dieting, it seems to be will-power that is
both strong and short-term.
was caused
by "ringing"
in the Step Response that one gets from suddenly producing growlies.
The answer was very clear - the curve was very smooth for the first few months
and it followed the Standard Decay Curve (decaying exponential) very well.
Furthermore, the other men were running into their own "yo-yos" and
were not doing as well overall.
That gives a horizontal line, which is what the app feeds back to you.
Responding to one number seems a lot less tricky than responding to growlies.
What remained was to add a layer of
strong filtering
to remove
To focus on jitter hides real but slow progress.