Lose Fat

People continue to ask whether they can lose "x" pounds by some specific date, usually because of a big social event. They don't know how this stuff works, so it's reasonable to wonder whether those diet pill commercials are legitimate. Lets show how to figure out how much weight a person can actually lose in a week.

The Basics: 

To lose fat, you must either eat fewer calories than you are eating now, or you must exercise more.  You may notice I didn't say "eat less"... this is because a healthy diet containing mainly protein, plenty of healthy vegetables, some fruits, and whole grains can be a whole lot of food. It can be more food that you're used to eating, in fact.  More on that later.

So, you have to make a caloric deficit in order to burn off that extra fat, either from food or exercise.  How much of a deficit? 3500 calories per pound to be exact. 

This works out to 500 calories per day to lose 1 lb per week 

(3500 calories / 7 days = 500 calories each day)

If you're looking to lose 2 lbs per week, then the deficit becomes 1000 calories per day. Up to here, this is pretty easy and reasonable for most overweight people to manage.   What if you want to lose a lot more per week? 

Losing more than 1-2 lbs per week: 

This is where it gets tricky. To lose more than 2 lbs per week, every week you have to make some intense changes in both diet and exercise. Most people who are not in the morbidly obese category cannot keep up this rate for more than a few weeks, but they can sometimes lose 5-8 lbs in the first week of dietary changes.  Lets show Greg as an example.

Greg weighs 275 lbs. His doctor says he should aim for 175 to be healthy. Greg has 100 lbs to lose, which is a lot. 

To sustain Greg's current 275 pounds without any exercise, he requires 2600 calories per day (this is how many he has been eating). By reducing his calories to 1500/day (the minimum value for men), he has made an 1100 calorie deficit. That's a little over 2 lbs per week already.   
Now, if he adds in 30 minutes a day of brisk walking, he can expect to knock that deficit up to 1500/day. That's 3 lbs per week, which is a decent pace for someone at his weight.  Greg will take between 33 and 52 weeks to lose all of his extra 100.  Why up to a year? Because...

Weight loss slows the smaller you become:

Now imagine Adam, who is much lighter than Greg. Adam is only eating 1600 calories to maintain his weight because he's pretty careful not to gain, but still wants to lose some pudge. Going down to 1500 only nets Adam 100 calories deficit... and that 30 minutes of brisk heart pumping walking only manages to get Adam up to 400 calories in deficit. Adam can only expect to lose about 0.8 lbs per week on the same exact diet as Greg. 

The ligher you are, the fewer calories you require to maintain your bulk. This means you cannot rely on food-reduction to be as large a part of your weight loss adventure, and must either go more slowly than Greg, or increase exercise substantially to stay at the same pace.

Extra carbs make you hold onto extra water:

What about that first week when it's not uncommon to lose 5-8 lbs? Why can't we keep that up? 

This is because changing your diet strictly away from junk and starchy foods immediately causes your body to shed water.  For every gram of carbohydrates your body contains, it must store 4 grams of water to support it.   For every 100 grams of carbs you eat and store, you're storing nearly a full pound of water.  100 grams of carbs is 3 ounces - that's roughly:

• 3 slices of bread
• 1.5 cups of rice or pasta
• 1/2 cup of sugar
• 1 sugar sweetened soda

You can imagine how quickly that water gets flushed out once you replace those carb calories with more protein, veggies, and healthy fats. But, after about a week, your new water level evens out and your body equalizes. 

Why Can't Fad Diets Work For Me?

Fad diets like the "Cabbage Soup Diet" or the "Green Tea Diet" are simply gimmicks to help people shed a few pounds for a very short amount of time. They work by restricting you to one or two foods, always something very low in both calories and sodium, high in water, and usually high in caffeine.  By eating practically no calories, no salt, more caffeine, and lots of water, you are essentially causing your body to dry up. Any diet under 1200 calories, containing little or no sodium and lots of water will make anyone lighter, but only from dehydration.  By reducing your calories far below the medical minimum and purging all of your body water you end up dehydrated with headaches, droopy skin, dry mouth and eyes, dizzy, and shaky from the lack of calories.  Once you begin eating real food again, even at the medical minimum amount, you *will* gain weight back even if it's just all that water you lost.  

Summary:

Be reasonable when it comes to how quickly you expect to lose weight. When you fail to lose 5 or 10 lbs in a week, don't get upset and think you've failed at being healthy -- because you haven't! It takes times to lose real fat, and it can take a really long time if you're already near your goal. 

Aiming for 1-2 lbs per week for the average dieter is a great goal, supported by doctors because it truly is sustainable. If you're aiming for 20 lbs of fat loss, then it could easily take you 10-20 weeks of healthy eating and daily exercise.  Don't be discouraged by this -- be empowered. Use it as proof to yourself that fad diets physically, medically, cannot work like you want them to, and that eating healthy is something you really must to do for your whole life if you want to be lighter.  Don't think of it as a diet. Think of it as living the life of a less fat, more healthy person, and eventually your body will catch up to your actions, no matter how long it takes.