Other than wasting away due to illness, there is no shortcut to weight loss.   You can, of course, simply not eat at all and that will work but if you resume your old habits you would gain the weight back and the drastic changes to your body might do harm.

Some people are motivated to lose weight - as long as it can happen right now.  And any number of gimmicks and diet programs will help, if you just buy the book or the meals.    But the failure rate is far greater than the success rate because, ordinarily, if people had the discipline to stick to a weight loss plan, they wouldn't be obese.    

Part of the reason a gimmick weight loss program might fail is that the neuroscience part of your brain knows what's better for you more than your conscious thoughts.  So if you've ever tried to lose weight and you suspect your body is working against you, a study published in Obesity says you may be right.

The study compared the effects of a short-term fast on two groups of mice. For 12 weeks, one group consumed a low-fat diet (10 percent fat); the other group was fed a high-fat (60 percent fat) and had become obese. The mice were then fasted for 24 hours. In that time, the leaner mice lost 18 percent of their body weight compared to 5 percent for the obese mice.

"When obese persons reduce their food intake too drastically, their bodies appear to resist their weight loss efforts. They may have to work harder and go slower in order to outsmart their brain chemistry," said Gregory G. Freund, a professor in the University of Illinois College of Medicine. 

Freund particularly cautions against beginning a diet with a fast or cleansing day, which appears to trigger significant alterations in the immune system that work against weight loss.   He also said that there may be an immune component to weight loss that has not been recognized."Take smaller steps to start your weight loss and keep it going," he said.  "Our data show that fasting induces an anti-inflammatory effect on a lean animal's neuroimmune system, and that effect is inhibited by a high-fat diet. Some of the brain-based chemical changes that occur in a lean animal simply don't occur in an obese animal." 

This breakdown occurs because obese animals resist downregulation of genes that activate the interleukin-1 (IL-1) system and associated anti-inflammatory cytokines.   Freund studied differences in the behavior of the two groups of mice, monitoring how much they moved, administering tests to discern the animals' ability to learn and remember, and noting whether the mice exhibited signs of depression or anxiety. 

The results suggest that beginning a diet with a fast or near-fast may alter brain chemistry in a way that adversely affects mood and motivation, undermining the person's weight-loss efforts.

"The obese mice simply didn't move as much as the other mice. Not only was there reduced locomotion generally, they didn't burrow in the way that mice normally do, and that's associated with depression and anxiety," he said.

Beginning a weight-loss program in a depressed frame of mind and with decreased motivation doesn't bode well for the diet's success, he noted.