Short Term Effects of the Zone Diet

The Zone Diet is a calorie-restricted diet created by Dr. Barry Sears that advocates higher intake of protein, moderate levels of carbohydrates, and moderate levels of essential fats. Each of these macronutrient servings is quantified by blocks with a prescribed number of blocks to be eaten at each meal or snack throughout the day. Short-term effects of the Zone Diet will vary from individual to individual depending how strictly the diet is adhered to and each user's reactions to food and calorie restriction.

Lack of Energy

Restricting dietary calories often leads to a lack of energy and an increase in irritability. This can be compounded by the Zone's reduced carbohydrate intake, which reduces glycogen supply in muscle tissues. Glycogen is what provides energy to activate muscles.

Constipation

With reduced carbohydrates comes the potential for less fiber in the diet from fruits and vegetables. Less dietary fiber often results in constipation or irregular and infrequent bowel movements.

Weight Loss

Zone Diet advocates have reported that individuals can lose at least five pounds in the first two weeks of the diet, followed by up to 1.5 pounds every week after, but some researchers have found otherwise. A study published in the July 2004 edition of "Nutrition Research" revealed that eight women who participated in a three-week Zone Diet experiment showed no significant changes in weight, body mass index, body composition or treadmill performance.

Reduced Performance

Researchers from Kingston University studied the effects of maximal oxygen uptake on eight men during a seven-day acute Zone Diet regimen. The maximal oxygen uptake, or VO2 max, was measured before and after the diet. The study revealed a significant reduction in time to exhaustion. Prior to the diet, the men reached exhaustion in 37.69 minutes. After seven days on the Zone Diet, the same men reached exhaustion in 34.11 minutes.

References

• Enter the Zone Diet: Zone Diet for Special Needs
• Weight Loss Resources: The Zone Diet Under the Spotlight
• "Nutrition Research"; Effects of Zone Diet Macronutrient Proportions on Blood Lipids, Blood Glucose, Body Composition, and Treadmill Exercise Performance; Michelle C. Bosse, et al.; July 2004
• "Journal of Strength and Conditioning Research"; The Acute 1-Week Effects of the Zone Diet on Body Composition, Blood Lipid Levels, and Performance in Recreational Endurance Athletes; Jarvis M. McNaughton, et al.; February 2002