How many times have you heard that you should eat more fruit to lose weight? Despite that traditional diet tip, a new study shows that boosting your intake of fruit does not result in a corresponding boost in weight loss, reported Headline and Global News on Friday.
Challenging the assumption that vitamin-rich, high fiber, low-calorie vegetables and fruits were ideal for weight loss, researchers from the University of Alabama at Birmingham discovered a "near zero" benefit. Their conclusion resulted from a meta-analysis of several studies.
However, the researchers were quick to emphasize the health benefits of fruits and vegetables. They expressed concern that the results would cause consumers to avoid produce, reported the Times Live on Friday.
But "all studies we reviewed showed a near-zero effect on weight loss," says study leader Kathryn Kaiser, Ph.D., instructor in the UAB School of Public Health. "So I don't think eating more alone is necessarily an effective approach for weight loss because just adding them on top of whatever foods a person may be eating is not likely to cause weight change."
The problem: People followed directions to eat more fruit and vegetables but added them to their existing diets rather than substitute eggplant for eclairs or mushrooms for muffins. "In the overall context of a healthy diet, energy reduction is the way to help lose weight, so to reduce weight you have to reduce caloric intake," Kaiser said.
She does feel that replacing high calorie foods with high fiber produce works. However, "our findings from the best available evidence show that effect doesn't seem to be present among people simply instructed to increase fruit and vegetable intake."
In contrast, multiple studies support boosting fat and protein while cutting carbohydrates, including carbs from fruits. The benefits included both weight loss and improvement for those with type 2 diabetes, exemplified in a study entitled "A randomized pilot trial of a moderate carbohydrate diet compared to a very low carbohydrate diet in overweight or obese individuals with type 2 diabetes mellitus or prediabetes."
Reported in PLoS One, the study compared participants on either a medium carbohydrate, low fat, calorie-restricted, carbohydrate counting diet (MCCR) consistent with guidelines from the American Diabetes Association or a very low carbohydrate, high fat, non calorie-restricted diet whose goal was to induce nutritional ketosis. The researchers included Dr. Stephen Phinney, a physician-scientist who has devoted three decades to researching diet and exercise.
Co-author of "New Atkins for a New You: The Ultimate Diet for Shedding Weight and Feeling Great," Phinney and his colleagues evaluated the participants based on factors such as weight and blood sugar. "Our results suggest that a very low carbohydrate diet coupled with skills to promote behavior change may improve glycemic control in type 2 diabetes while allowing decreases in diabetes medications," he concluded.
All participants in the clinical trial lost weight, but those on the high fat low carb ketogenic diet lost more weight. They also experienced a reduction in hunger. Phinney includes complementary studies in "The Art and Science of Low Carbohydrate Living: An Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable."
What of the traditional advice that athletes should load up on carbohydrates? Wrong, say Phinney and his colleagues Jeff Volek and Tim Noakes. The trio co-authored an essay in the online version of the British Journal of Sports Medicine reporting on low-carb diet athletic performance studies.
Nine of 11 low-carb performance studies indicated that participants did better or the same. "Studies of elite athletes chronically adapted to low-carbohydrate diets have uncovered one unexpected finding–their extraordinary ability to produce energy at very high rates purely from the oxidation of fat," wrote the authors.
The studies have been an ongoing project for Phinney. In 1983, he produced a research paper showing that after following a low-carb diet for three weeks, cyclists burned significantly more fat.
In addition, they had a "four-fold reduction in muscle glycogen use" compared to high carb diets. Phinney and Volek also include their own studies in "The Art and Science of Low Carbohydrate Performance."