Prepare For Weight Loss, Part 2: The Energy Balance Equation
An old joke from my medical school days asks, “How many psychiatrists does it take to change a light bulb?” Only one, but the light bulb must want to change.
How many weight-loss programs does it take before you lose that weight for good? Only one, but…
Where does the fat go when you lose weight dieting? Metabolic reactions convert it to energy, water, and carbon dioxide, which weigh less than fat. Most of your energy supply is used to fuel basic life-maintaining physiologic processes at rest, referred to as resting or basal metabolism. Basal metabolic rate (BMR) is expressed as calories per kilogram of body weight per hour. Even at rest, a kilogram of muscle is much more metabolically active than a kilogram of fat tissue. So muscular lean people sitting quietly in a room are burning more calories than are fat people of the same weight sitting in the same room.
The major determinants of BMR are age, sex, and the body’s relative proportions of muscle and fat. Heredity plays a lesser role.
Energy not used for basal metabolism is either stored as fat or converted by the muscles to physical activity. Most of us use about 70 percent of our energy supply for basal metabolism and 30 percent for physical activity. Those who exercise regularly and vigorously may expend 40–60 percent of their calorie intake doing physical activity. Excess energy not used in resting metabolism or physical activity is stored as fat.
If you want to lose excess weight and keep it off, you must learn the following equation:
The energy you eat,
minus the energy you burn in metabolism and activity,
determines your change in body fat.
Or, more succinctly:
Energy Intake minus Energy Expenditure Equals Change in Energy Stores
This is the Energy Balance Equation.
Energy is measured in calories. For example, if you eat 2,000 calories of energy daily, but burn up 2,300 calories daily, you will have a negative energy balance and your fat stores will go down. That is, you lose weight.
Now, a pound of body fat contains 3,500 calories, so you have a way to go before you lose a pound on the bathroom scale.
Overweight and obesity result from an imbalance between energy intake and expenditure.
It’s just that simple. The degree of this imbalance is quite small. Over the course of a year, you will gain three and a half pounds of fat just by adding a teaspoon of butter to your dinner roll every day, assuming all other variables are unchanged. Simply avoid a 10 minute walk daily for a year and you will gain five and a half pounds. Taking the walk and avoiding the teaspoon of butter sound easy, and they are, but if not done you will gain 35 pounds over the course of five years.
While we don’t have much control over our basal metabolic energy requirements (roughly 1,200–1,500 calories daily), many of us are able to adjust food intake and activity levels to strike a happy balance in the energy equation, minimizing unwanted fat. For a lucky few, that desirable balance is automatic and unconscious. The rest of us have to think about it, work at it, make it a priority at times.
Right now your balance is tipped in favor of excess energy stores (fat). It will soon be tipped in the other direction. You will convert fat to energy and lose weight in the process. Once you achieve your goal weight, the energy equation must be balanced again.
There is no doubt that the energy balance equation applies to you. People who swear they can’t lose weight on extreme low-calorie diets have been locked up (with consent) in university medical center metabolic wards with access to food strictly controlled by staff. On appropriate calorie-restricted diets, everyone loses weight. When an exercise program is added, they lose more weight.
December 7th, 2008 at 9:37 am
[…] Advanced Mediterranean Diet Blog Ruminations on Weight Loss, Health, and Longevity Via the Mediterranean Diet « Prepare For Weight Loss, Part 2: The Energy Balance Equation […]
December 8th, 2008 at 4:19 am
I love your blog but for this post I simply disagree. Our bodies are not so simple as to put such a meaningless equation on to them. If you exercise for 10mins more a day your body could simply compensate by lowering its metabolism. This has been shown in many animal studies. I had tried for years to lose weight by increasing exercise and eating less and it simply did not work. My biological urges to eat were overwhelming and even when I did manage to control them I still did not lose FAT just weight (ie muscle tissue). More studies on animals show that under calorie restriction and increased exercise the animal loses more muscle mass and the body holds on to the adipose tissue as best it can. It wasn’t until I lowered my carb intake and subsequently my insulin levels lowered that my body started to give up the fat in my adipose tissue. Now it is not hard to lose the weight and I have dropped over 10kg.
December 8th, 2008 at 9:19 am
Hi, Dr Dan.
Around the middle of my post above is a carefully chosen phrase: “…assuming all other variables are unchanged.”
You are right to imply that someone trying to lose fat weight simply by adding a 10-minute walk to their routine daily will fail. Rather than metabolic rate slowing as compensation to maintain a steady weight, I think the person more likely adds a few food calories, and it wouldn’t take many, so weight is unchanged. At least two variables have changed in this case, not one.
Starting a moderate or vigorous exercise program alone, as a weight-loss program, works for some men but very few women, and usually only for 2-5 kg of weight. [These are generalizations, so there are always exceptions.]
Loss of lean tissue mass (e.g., muscle) is indeed a problem on many diets, especially with more severe calorie restriction. That’s less of an issue on moderate- and high-protein diets compared with low-protein diets. And exercise tends to counteract the loss of muscle mass.
“Starvation diets” do slow metabolic rate in humans, but I’m not convinced that mild caloric restriction slows it to a clinically significant degree.
Congratulations on the 10 kg weight loss! I remember when I followed Dr Atkins diet I lost about 8-10 pounds straight away, then nothing despite good compliance. But I may have been in the healthy BMI range the whole time. I only had another 5 pounds of “vanity fat” I wanted to lose.
[For anyone interested, Dr Dan has good photos of low-carb meals at his blog, among other stuff.]
-Steve
December 12th, 2008 at 2:42 pm
I agree with Dr Dan, you didn’t quite emphasized the role of insulin in your equation (maybe you’ll get to it later, I’ve just found your blog and started reading the weight loss series from #1).
December 13th, 2008 at 11:11 am
Welcome, zbiggy! Thanks for your comment.
Insulin and glycemic index have been very popular for the last 5-10 years, in explanations of excess body fat. But I’m not convinced they should have the preeminent role.
In terms of losing weight and keeping it off, a person can be successful without knowing about or understanding insulin and glycemic index. In my view, the Energy Balance Equation is preeminent.
-Steve
December 13th, 2008 at 4:58 pm
well, as for what I know the EBE is critical in the weight loss phase - i.e. you must create a caloric deficit in order to lose, but even then if you pick your calories mainly from fats and proteins, you are full sooner and for longer, comparing to a situation when you are restricting calories but live mostly on easily digested carbs.
So if your BMR is 2500 and you take in ~2000 the difference between e.g. grains+beans diet and e.g. bacon+tomatoes diet is that on grains you’d go hungry all day and commitment could be more difficult.
Another story is when you are at your target weight and want to maintain. Then, on grains+beans your insulin is high and glucagon is low and this is when all additional (i.e. over 2500) carbs or fats will be stored in the body(and it’s not hard to take in something in addition since you frequently have a sweet tooth on high carb).
But when you keep your carbs low then your insulin is low and glucagon is high and you can actually get away EXCEEDING these 2500kcals - you will not lose but if you happen to eat some more n hundred kcal of fat it will not land in your hips but will be neutral to your weight.
This is somehow low-carb Atkins- and Eades-wise point of view.
December 14th, 2008 at 10:27 am
zbiggy, are you saying that a low-carb, unlimited fat/protein diet cannot lead to excess fat weight? If so, I’ll have to modify the EBE. I’m not aware of the data, but it may well have been studied. Easy enough to do so.
I agree that meals with significant protein and fat lead to greater satiety and could help the problem of over-eating. That may explain why several studies show greater efficacy with low-carb diets when compared with low-fat diets.
Unfortunately (?), low-carb weight-loss diets tend to have a higher drop-out rate than low-fat or more “balanced” diets such as the Mediterranean. I’m thinking of the New England Journal of Medicine study last July that had a 22% drop-out rate for the low-carb cohort. But that thing has been debated to death. Here’s a link to my take:
http://advancedmediterraneandiet.com/blog/?p=56
-Steve
December 14th, 2008 at 2:44 pm
“, are you saying that a low-carb, unlimited fat/protein diet cannot lead to excess fat weight? If so, I’ll have to modify the EBE.”
my evidence is rather anectodal but consider one example: a person with type 1 diabetes can eat whatever they want but due to their luck of insulin they will lose weight. So the EBE must have something added, to your original sentence:
“The energy you eat,
minus the energy you burn in metabolism and activity,”
I would add something like
“minus the energy wasted”
- this would also cover e.g. cases of diarhorrea etc.
So, an otherwise healthy person who eats a heap of fat (over his daily requirement) but little carbs will - at least I believe so - keep his weight on such a day and not gain any. I once found a diary in the internet - an experiment (amateurish) done by a young man who lived high fat, low carb for 30 days and his average kcals intake was definitely over his need but his weight stayed unchanged during this month. Unfortunately I can’t find this site but anyway, it is not a scientific proof.
As for drop-out rate from low-carb - I agree, I have been on my kind of diet for 14 months already and have internalized it completely and it’s just a part of me now but I agree that for someone who can’t imagine their life without pasta, pizza etc, this may be not a fortunate option
and they could be happier with let’s say portion-control or some other mechanism.
December 14th, 2008 at 2:46 pm
sorry “lack of insuline” not “luck”