Could you lose 11 pounds in 4 days?

"Losing weight is simple: Ingest fewer calories than your body burns."

However as we all know, easier said than done. For example, to burn off a single chocolate chip cookie (78 calories) requires approximately 20 minutes of walking at a moderate pace (225 calories/hour).

Most people pursue a conservative approach of a small decrease in food intake or a small increase in energy expenditure to lose weight gradually. The problem is that such slow progress can be discouraging. The alternative is a very sudden and rapid weight loss as described in a recent study (reported on by the New York Times):

"Researchers in Spain and Sweden had 15 healthy but overweight Swedish men restrict their calories to about 360 a day, a reduction of approximately 1,800 calories. What calories they did ingest came in liquid form: Some men drank mostly sugary carbohydrates, others a high-protein drink. The men also exercised — a lot. Their days began with 45 minutes of cranking an arm-pedaling machine for an upper-body workout. Then, as a group, the men strolled for eight hours across the Swedish countryside, with only a 10-minute break every hour. They were allowed as much of a low-calorie, sports-type beverage as they wanted during their walks."

Wow. 360 calories a day is equivalent to 4 chocolate chip cookies. Imagine surviving a whole day on 4 chocolate chip cookies while walking for 8 hours (225 X 8 = 1800 calories in addition to your basal metabolic rate).

Not surprisingly,

"After four days, the men had each lost almost 11 pounds, with nearly half of that coming from body fat; the rest of the loss came primarily from muscle mass. The researchers had anticipated that the high-protein drink would protect people against muscle-mass loss. In fact, the losses were the same, whether the men had been given sugar or protein."

Interestingly half of the weight lost was fat and half was muscle, and so there was a cost of this extreme dieting in terms of lost muscle, along with the benefit of lost fat. However the real story is that the 11 pounds were not immediately regained:

"More surprising, the men did not immediately put the weight back on after the study ended. “We thought they would overeat and regain the weight lost,” Dr. Calbet says. Instead, when the volunteers returned a month later, most had lost another two pounds of fat. And a year after the experiment, they were still down five pounds, mostly in lost body fat."

The explanation offered by the study authors was that perhaps "the men were inspired by their hypercompressed success to change their lifestyles. The men moved more and ate less than before."

Indeed I would offer the following explanations of why the weight loss persisted for over a year: 1) As stated above, the subjects received positive reinforcement that they could lose weight; 2) the subjects did not want their suffering to be in vain and so they kept the weight off; and 3) the 4 days really hammered home the message that ingesting fewer calories than your body burns will result in significant weight loss.

So could you lose 11 pounds in 4 days? The answer is yes you could lose a significant amount of weight (maybe not 11 pounds unless you are overweight), but I would offer the following cautionary note from Greg Ferenstein who subjected himself to an even more extreme 4-Day diet of only 220 calories per day:

"Technically, yes. But while the 4-Day Diet’s plan of all-day walking and near starvation may trim your waistline, your hunger pangs may be met with bizarre side effects such as peeing blood. Still interested?"

The diet was a success reproducing the general trend from the study described above:

"Like the participants who lost an average of 11 pounds in a mere 4 days, I also rapidly lost fat: I dropped 1.3 percent body fat, which is about twice as fast as my previous diet (0.7 percent in a week). Even more extraordinary, like those in the research study, I keep shedding my waistline—two days after returning to my normal diet, I’ve lost another 0.5 percent in 2 days." 

Note that Mr. Ferenstein does not mention how much weight he lost which is probably less than 11 pounds because he may not be overweight like the subjects in the Swedish study. He did lose a significant amount of body fat. However, Mr. Ferenstein once again offers the following medical caution:

“People should not try to do this on their own. I strongly advise anyone trying to do this type of intervention to do it under medical control.”

Ingest fewer calories than you consume -- that is the take-home lesson. How you do it is up to you. Although if you do decide to subject yourself to one of these extreme diets, please take the necessary medical precautions.

Figure 1. Extreme dieting can work but be careful.