Thursday, November 12, 2009

Secrets To Weight Loss - Part One

It's disturbing that in the United States, two-thirds of Americans are either overweight or obese. As a doctor, it is one of the most common problems I address, even if a patient doesn't ask me to. Got a cold? Feeling stressed? Want a physical? Rolled your ankle?

Has anyone ever discussed your weight? Are you concerned about your weight? What have you tried for weight loss? What did you find successful?

In this series, I'll reviewed my discussions with patients so you understand what it will take to lose weight and keep it off.

Losing weight is hard work and frankly can be a difficult and lonely experience since the majority of Americans are overweight or obese. The problem of heaviness in this country is only becoming worse.

First some basic concepts. Overweight is defined as a body mass index or BMI greater than 25 and less then 30. Obesity is a BMI greater than 30. Morbid obesity is a BMI greater than 40. Calculate your BMI. Although BMI isn't perfect, unless you are a high performing athlete (not a weekend warrior) and have significant muscle mass, BMI is a reasonable way of determining which category you fit into.

Second, the body does not lie. Unless you have some sort of medical problem like a low functioning thyroid (hypothyroidism) or other less common hormone problem, your body does not lie. If you eat exactly the same amount as you burn, then you will not lose or gain weight. Eating less and burning more consistently will cause weight loss. Eating more and burning less will result in weight gain. Simple concept. What goes in must equal what goes out to maintain weight. Any alteration in this simple equation causes weight loss or weight gain. The body does not lie.

Third, I don't think you overeat to the degree you think I do. Patients invariably tell me that they eat very little and certainly a lot less than their friends or family. While I know individuals aren't eating a Thanksgiving dinner or eating an entire large pizza for lunch daily, weight loss requires a caloric intake less than the output. Note the previous point the body does not lie. If a person did eat a lot, he would continue to gain weight, not maintain.

Fourth, you need to understand basic math. Know this number. 3500. An addition of 3500 calories equals one pound. If your body has 3500 calories left over, then you gain a pound. Burning 3500 calories, then you lose a pound. Sounds like a lot of calories, doesn't it? But it's not. If you drank a can of regular soda daily (and yes, diet doesn't count as it has zero calories), then that is an extra 130 calories per day. In 27 days less than one month you would gain a pound (3500 / 130 = 27). In one year you would be 12 pounds heavier.

Fifth, think of calories as money and your weight as a savings account. Your savings account goes up or down depending on how much you save. Put more into the bank and withdraw less? More in your savings account. Taking out more than you put in, the amount in the savings account falls. Your bank doesn't care if you deposit $100 in pennies or in a crisp C-note. Skipping the discussion of nutritional value, your body doesn't care if the 2000 calories you are supposed to ingest comes all via salad greens or the equivalent of a box of chocolates. Money is money. Calories are calories regardless of how you get them.

Sixth, your body is built for survival and isn't stupid. Go back to the previous point. Your weight is a savings account and to keep it level what goes in equals what goes out. If all of a sudden, your income gets cut then to make ends meet you must take withdrawals from your bank account. If the income doesn't return to previous levels, then the savings account continues to get smaller.

Faced with this situation of being unable to restore deposits to previous levels, would you continue to spend as much? Of course not. To avoid bankruptcy you would make hard choices like downsizing your expenses and making adjustments. As a result you slow down the outflow of money so that eventually the amount that you spend is equal to the new decreased amount coming in.

Your body is built for survival and isn't stupid either. Faced with a budget crisis, that is a diet where calories coming in is less than what is burned, initially the body hasn't had adequate time to make adjustments. It depletes its savings resulting in weight loss. But since it is built for survival, it will make adjustments necessary to that its expenditures exactly made your diet. You no longer lose weight. Your body doesn't know whether it is on a desert island or living in the United States where food is plentiful, but all it knows is that its caloric budget was cut. It needs to keep you alive until it can find its next meal. Adjustments are made. Weight loss stops. Naturally, it will deplete fat first, then muscle. So don't worry about that being a reason not to being weight loss.

Seventh, the vast majority of patients I see weren't overweight or obese to being with. Weight gain typically occurred after high school or college, job change which was less physically demanding, after pregnancy, and as they got older. Sadly this isn't the case today where children are increasingly obese and will be the first generation of Americans not to live as long as their patients because of weight related medical problems.

Finally, the success to long term weight loss is permanent reduction in calories and increase in physical activity. It's not a diet but a lifestyle change. You can lose weight in the short-term with fewer calories, which is the reason why gastric bypass works. However, long-term weight loss requires physical activity.


Suxiao said...

Hi Dr. Liu,

I read your comment on NYTimes Well Blog and was intrigued by your comment on the Primary Care article. I am a CT resident applying to medical school this year and was wondering:

What about primary care made it appealing to you?

I know UConn has a great primary care program- did many of your classmates also choose primary care?

What is a primary care doctor's lifestyle like? My shadowing experience has only been with surgeons...

Sorry for all the questions... I am going into medicine because I want to help people and I really don't mind "low wages" or the low reputation that the article mentions. So far, actually, the seemingly personal practice of a PCP is what attracts me the most.

S. Yang

Davis Liu, MD said...

Contact me at so I can answer your questions directly.


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