Self-selected, balanced diets can help with weight loss even without regular nutritional supervision

27 Jan 2020 --- Overweight adults following the Mediterranean, Intermittent Fasting (IF) and paleolithic (paleo) diets were able to lose excess weight, although adhering to the diets dropped off considerably during the one-year study, according to new research from the University of Otago, New Zealand. While the 250 participants lost 2-4 kg on average, those choosing the fasting or Mediterranean diets also demonstrated clinically significant improvements in blood pressure. The study reveals that people following self-chosen diets with little supervision can still have realistic, health-positive outcomes.

“The findings provide some evidence that fasting and paleo diets can be healthy eating approaches and lead to weight loss and improvements in health over the longer term. They suggest that any dietary pattern that promotes choosing mainly fresh and unprocessed foods, and decreasing energy intake is likely to be beneficial,” Dr. Melyssa Roy, a Research Fellow at the university’s Department of Medicine, tells NutritionInsight.

The study’s results came as little surprise to the research team. “We found that different diets could work for different people in the ‘real world’, but the changes achieved without ongoing support were quite modest. This seems consistent with what is observed in the general population,” she continues.

Study parameters
The participants showed small differences in metabolic outcomes on self-selected diets without intensive ongoing dietary support, even though their dietary adherence declined rapidly. Fifty-four percent of the participants chose the fasting diet, while just over a quarter chose the Mediterranean and 18 percent chose the paleo.

“Paleo and IF were very popular diets when the study was designed in 2014/15 and there was some evidence from published trials that they could be effective, but it was not clear if they actually worked under real-world conditions. The Mediterranean diet was chosen as a comparison diet because it represents best practice and is known to be beneficial for weight loss and improving health,” Dr. Roy explains.

After 12 months, the Mediterranean diet had the best retention rate with 57 percent of participants continuing having lost an average of 2.8 kg, while of the 35 percent still on the paleo diet, the average weight loss was 1.8 kg. The IF participants limited their energy intake to about 25 percent of their usual diet (500 kcal for women and 600 kcal for men) on two self-selected days per week. Fasting led to slightly more weight loss than other diets, with an average of 4 kg lost.

“While there could be differences due to the timing of fasting, we considered that overall the restriction of energy intake was the most important factor in fasting, however people wanted to do it,” Dr. Roy notes.

Regardless of which diet the participants adhered to, each group showed signs of weight loss.Simultaneously, one of the advantages that fasting had was that participants didn’t have to consistently change the way they ate all the time. Likewise, fasting doesn’t require a lot of preparation or expense, Dr. Roy highlights.

Regardless, the researchers observed that the fasting group struggled with meeting the calorie restrictions. While many of them tried to fast two days a week, they tended to eat more than the guidelines of 500 kcal for women and 600 kcal for men.

Investigating why the Mediterranean diet was the easiest to stick with has only yielded “some anecdotal answers” from the participants, Dr. Roy notes.

“Those following the Mediterranean diet were able to follow the guidelines quite closely, suggesting that those guidelines are easier to achieve on a regular basis, in our food environment. Those following paleo struggled to avoid grains and sugary, sweet foods. Most continued to have these foods weekly or more,” Dr. Roy’s colleague Dr. Michelle Jospe, Postdoctoral Fellow and Registered Dietitian, also tells NutritionInsight.

Continued research
Dr. Roy notes that the question surrounding the factors determining which diets will be successful for different people exceeded the scope of the current research. “This paper has not specifically answered this but we are preparing another paper that does,” she explains.

Further analysis is also planned to examine how personality and psychological variables interact with diet and exercise choices and their outcomes.

Dr. Roy states the evidence shows that for some people, the Mediterranean, fasting or paleo diets can be “healthful, beneficial ways to eat.” Moreover, the study supports the idea that there isn’t a single “right” diet – there is a range of options that may suit different people and be effective.

On a similar note, the UN Food and Agriculture Organization continues to promote adhering to the Mediterranean diet, alongside the New Nordic and traditional Japanese diets, to ensure people receive “food that not only feeds but also nourishes them.”

By Anni Schleicher

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