Depending on which diet plan you choose to lose weight, it may be a good idea to take a general multivitamin/mineral supplement, found a study by Stanford University researchers.

For the study, lead researcher Christopher Gardner and colleagues looked at data from 300 overweight or obese women who were randomly assigned to follow one of four popular weight loss diets: The Atkins Diet, the Zone Diet, LEARN (Lifestyle, Exercise, Attitudes, Relationships, Nutrition) or the Ornish Diet.

Regardless of the diet, the women started out eating about 2000 calories per day. Over the course of the two-month study, they had reduced their caloric intake to about 1500. The women were surveyed randomly — and without warning — three times during the study. They were asked to recall what they had eaten over the previous 24 hours. The responses were then sorted according to diet plan and averaged.

With the women eating less, and in some cases avoiding entire food groups, it probably comes as no surprise that they were also missing out on vitamins and minerals. Carbohydrates, for example, are excellent sources of many of the B vitamins. A reduction in fruit intake could significantly affect one's intake of vitamin C and potassium.

Zone Diet

In the study, those on the Zone diet were least likely to have inadequate consumption of the measured vitamins. The researchers suggest that because the diet plan is more balanced in the macronutrients than most (carbohydrates, protein and fat), a dieter is less likely to become deficient. The Zone diet suggests 40 percent carbohydrates (from whole grain sources and not refined sugar), 40 percent protein (using lean meats), and 30 percent fat (with a focus on unsaturated and omega 3 fats).

Atkins Diet

The Atkins diet promotes the most severe restriction of carbohydrate foods. Depending upon the phase of the diet someone is on (and therefore the level of carbohydrate restriction), people run the greatest risk of becoming deficient in Vitamin B1 (thiamin, found in breads, pastas and other flour products), vitamin B2 (riboflavin, also found in bread), and vitamin C (fruits). Those on the Atkins diet can prevent this by choosing low-carb foods wisely. For example, a daily serving of leafy greens will provide all three of these nutrients with very little carbohydrate or calories.

Ornish Diet

The Ornish diet is often considered the complete opposite of the Atkins diet. Dr. Dean Ornish created the vegetarian diet that is extremely low in fat (10 percent of calories), moderate in protein (20 percent) and very high in carbs (70 percent). The nutrients at most significant risk of becoming deficient are the fat-soluble vitamins — A, E, D and K. Also lacking in this diet are Omega-3's, which are not always included in multivitamin supplements, yet are thought to be essential for good health.

LEARN Program

The LEARN program is less about prescribing a specific meal plan to dieters, but offers advice to improve the patient's relationship with food to prevent overeating, make healthier choices and increase physical activity. Again, depending upon the foods chosen, less-than-adequate levels of vitamins may be consumed.

"Our bodies work best when vitamin and mineral deficiencies are absent, and healthy food is the best way to get enough of these important nutrients," said Dr. Michael Dansinger of Tufts University School of Medicine in Boston, and adviser for the television series "The Biggest Loser."