DEAR DR. BLONZ: I went on a detox/cleansing diet routine, with a drink and pills, that was recommended by my friend. I was able to drop almost 10 pounds in a few days. It was incredible until the intensive part of the routine was over, and the weight began to return within a week. Did I do anything dangerous? Was there anything I could have done so that the weight stayed off?

G.M.

DEAR G.M.: The goal of losing "weight" can actually be a bit deceptive, because the number on the scale can vary for many reasons. More appropriately, the goal should be to reduce excess body fat. Some regimens can be very successful at taking off pounds, but they fail to make any significant dent in our stores of unwanted body fat.

As the body's most calorie-dense material (nine calories per gram), fat is our main form of energy storage. Whenever the intake of calories exceeds the demand at the moment, all the excess, whether from carbohydrate, fat or protein, is converted to fat and then shuttled away to storage. That means that at mealtime, the flow is toward storage, while between meals the flow is from our fat stores to the working muscles and organs.

A pound of body fat is estimated to contain about 3,500 calories of potential energy. It is reasonable to consider, therefore, that the number of calories burned has to exceed dietary intake by something in the neighborhood of 3,500 for every pound of body fat to be lost.

In the 2010 Dietary Guidelines for Americans, adult men reported an average daily intake of 2,640 calories, while women reported consuming an average of 1,785 calories each day. These numbers can vary according to age, body size and level of activity, but you can see that even if one were to cut one's food/calorie intake by half, it's difficult to lose much more than a couple of pounds of body fat a week.

How to explain your results? Cleansing routines often talk about pounds of "toxins" clinging inside your intestines, but there is not much evidence to support such claims. What is known is that there is usually a quantity of fecal matter in queue for normal elimination. Any "cleansing routine" that includes laxative ingredients will cause a temporary -- albeit dramatic -- weight loss due to the physical weight of this matter. If it also contains diuretic ingredients, the cleansing product can cause a loss of water weight; again, a temporary effect. Neither of these is the same as weight loss that involves a decrease in body fat from the adipose stores. Once the cleansing regimen is finished, the body re-establishes balance and the numbers on the scale return to where they were.

Success takes determination and a good plan. There has never been a quick fix that has withstood the test of time. Relying on a cleansing diet drink, or diet pills, does not bode well for long-term chances. Better to find a plan that includes a healthy, balanced diet, a good selection from all the food groups and a solid activity component. By tweaking your food choices, lowering calories and increasing activity, your new routine can bring lasting success.

Kensington resident Ed Blonz has a Ph.D. in nutrition from UC Davis. Email him at cctimes@blonz.com.