Diet

How Can I Lose Weight?

It sounds so simple - eat less than you burn, and you'll lose fat at the rate of 1 pound of weight per 3,500 calories.

And this, in my experience, is absolutely true.

However, there are a number of extra considerations that work against the dieter. This page covers them, and how to overcome them.

A rough summary:

• before you start dieting
  • read "The Hacker's Diet" and use its website for daily tracking throughout
  • measure weight daily for at least a month before you embark on a diet
  • figure out how to get your desired calorie deficit by basing it on what your weight trajectory is telling you
• aim for 1-2lb a week weight loss rate (unless you have a lot of fat to lose)
  • absolute maximum safe weight loss is 31 calories per day, per pound of fat you have
  • but you should aim to keep safely inside that level, not treat it as a target
  • if you bust that target, you'll start getting muscle etc broken down and that is not a good thing
• a single "cheat day" might put several pounds of "water weight" on overnight - if so it's not fat and will come off again just as quickly
• don't eat sweeties/similar as your blood sugar and appetite will get kicked all over the shop
• evidence on hormones (leptin, ghrelin) is contradictory and unclear
  • in particular, it doesn't seem to be true that the body's reaction to a diet necessarily ends up making these work against you
• the "water weight" you lose at the start will reappear at the end of the diet - don't forget to account for this

How do I know how many calories I'm consuming? And how do I know how many calories I'm burning?

Any number of experiments have indicated that people are terrible at working out how many calories they consume.

Also, while there are a large number of online calculators that aim to estimate your base calorie burning rate given your sex, age, height and weight, these are not guaranteed to be accurate. Maybe your metabolism is faster or slower than the norm.

The way to overcome both of these problems is to ascertain the difference between the two when following your current normal eating habits. To do this, use a weight tracker such as the one found in "The Hacker's Diet" (see below), and track your weight for at least a month before doing anything else. This will tell you at what rate you are currently gaining or losing weight. You can then plan your diet based upon this.

For instance, say you're gaining a pound a month. That's 3,500 calories a month, something like 110 a day. So you need to alter some combination of your exercise habits and diet to compensate for that 110 a day, and then additionally cut out however many more calories are required for your target weight loss - e.g. averaging saving another 500 calories a day will then mean you can expect to lose a pound a week. Keep that up for a year and that's 4st 10lb.

How quickly can I lose weight?

The range to aim for is often quoted as 1-2 pounds a week: fast enough to give positive feedback, but not so fast your body starts breaking up non-fat tissue in order to keep things going. You may manage more than this at the start if you are very overweight, since you will be burning more calories just to keep all that bodyweight going, and you will have more fat cells to release energy.

But what's the limit? See A limit on the energy transfer rate from the human fat store in hypophagia (J Theor Biol. 2005 Mar 7;233(1):1-13.)

A limit on the maximum energy transfer rate from the human fat store in hypophagia is deduced from experimental data of underfed subjects maintaining moderate activity levels and is found to have a value of (290+/-25) kJ/kgd. A dietary restriction which exceeds the limited capability of the fat store to compensate for the energy deficiency results in an immediate decrease in the fat free mass (FFM).

Now 290 kJ/kg = 31.3 kcal/lb, so the experiments indicate that the absolute maximum you'll get from each pound of fat is just over 30 calories/day (here I'm using "calories" = kcal)

In terms of how much body fat one has to play with: from https://greatist.com/health/how-to-measure-body-fat#how-to-measure-body-fat, and inch measurements in 86.010 x log10(abdomen – neck) – 70.041 x log10(height) + 36.76 I'm getting about 17%, about 31 pounds of fat in my case. So max release a bit over 900 calories/day. 10 pounds lower than that and 700 calories/day (1.4 pounds a week) stops being possible.

In any case, it's a good idea to be very careful here - if the body runs out of fat fuel, it will cannabalize muscle. And your heart is a muscle.

What about water weight?

You have an additional quick-release energy storage mechanism: glycogen. In conjunction with the water bound to it, the energy storage density is around 1 calorie per gram (about 450 calories per pound), around an eighth of the energy density of fat.

The upshot is that 4-5 pounds of glycogen+water might hold about 2000 calories. So if you have been following a low-carb diet and then pig out on lots of pizza then your weight can go up 5 pounds or more the next day, maybe more from water retention from the salt in the pizza.

The good news is that this weight will go away again as quickly as it came. But in the meantime it can be very demoralising. This kind of consideration is why it's so helpful to track a rolling average of weight, rather than focus on each day's reading. The weight tracker for "The Hacker's Diet" calculates the trend as (9/10)*yesterday + (1/10)*today. This does a good job of smoothing out bumps in the road. Note that it does mean that the calculated trend will lag your actual weight if you are streadily losing (or gaining) - by about 9 days in the long run if the gain/loss stays constant over a period of 3 weeks or more.

Stay off refined carbs

From the standpoint of appetite management, refined carbs are not your friend. The body will hoover them up, bind them into glycogen, and then your blood sugar level will nosedive, leaving you feeeling hungry again.

Examples of simple carbs: sugars and refined grains that have been stripped of all bran, fiber, and nutrients, such as white bread, pizza dough, pasta, pastries, white flour, white rice, sweet desserts, and many breakfast cereals. Sugars here are glucose, fructose, sucrose

Examples of complex carbs: Whole grains, Whole grain bread, Brown rice, Legumes, Nuts, Lentils, Sweet potatoes, Quinoa, Granola, Some varieties of vegetables

Potatoes, while technically complex carbs, are actually unusually quick to break down and so function more like refined/simple carbs.

Leptin and Ghrelin

High fat levels => high leptin => less hunger, more energy expenditure

When your body thinks you have low leptin, you get these changes (mediated via the hypothalamus):

• Eating more: Your brain thinks that you must eat in order to prevent starvation.
• Reduced energy expenditure: In an effort to conserve energy, your brain decreases you energy levels and makes you burn fewer calories at rest.

One theory as to why obesity can be so hard to shake is that, beyond a certain level of fat, the body can develop leptin resistance/insensitivity - meaning the feedback loop is broken.

Ghrelin gets made by the stomach when empty. So high ghrelin => hunger.

Again, there is a theory that obesity may induce additional ghrelin sensitivity, making it harder to shed pounds.

So all things considered, low grehlin and high leptin would seem to be good things in a dieter. However the evidence doesn't line up with this - at least one study indicated that those better at losing weight had lower leptin and higher ghrelin than others - in each case, the opposite of what we might expect: https://www.precisionnutrition.com/leptin-ghrelin-weight-loss

At the moment, the best anyone seems able to say about this is "it's complicated". One heartening takeaway is that while diets might tend to elevate ghrelin response to an ampty stomach, this doesn't actually seem to be a sure-fire predictor of rebound weight gain, as it's the body's response to a given ghrelin level that is the important thing.

Ending the diet

Note that once you're back to a more normal regime, you'll get water weight back on again - maybe an extra 4 or 5 pounds. Cater for this when you're setting your target weight.

The Hacker's Diet

This sets out the calorie-control approach to dieting: theory and practice both. A key insight is that tracking a rolling average of weight means the dieter avoids the psychological stress of the everyday ups and downs and can focus on the far steadier trend.

Links:

• Explanation of diet: https://www.fourmilab.ch/hackdiet/e4/
• Weight tracking: https://www.fourmilab.ch/cgi-bin/HackDiet/