Clinical Trial of Low Fat Plant Based Diet

[Jinzang]

A one year randomized clinical trial was performed in New Zealand on low fat whole food plant based diet as a method to reduce weight and lower cholesterol. The people who followed the diet lost an average of ten pounds without exercise or restricting eating. The full study is online, here is an extract from the discussion section.

This randomised controlled trial compared a 12-week Whole Food Plant Based (WFPB) dietary programme to normal care alone. The intervention led to significant and sustained BMI and weight reduction at all measurement points compared with the control group. To the best of our knowledge, there are no randomised controlled trials that have achieved a greater average weight loss over a 6- or 12-month period, without mandating regular exercise or restricting total caloric intake. The key difference between this trial and other approaches to weight loss was that participants were informed to eat the WFPB diet ad libitum and to focus efforts on diet, rather than increasing exercise. The mechanism for this is likely the reduction in the energy density of the food consumed (lower fat, higher water and fibre). Multiple intervention participants stated 'not being hungry' was important in enabling adherence. Intervention participants were highly adherent with the dietary changes, although this decreased with time.

Our results show a reduction in cholesterol for the intervention group at all measurement points, and in the control at 3 months only. Between-group analysis showed statistically significant differences in cholesterol at 3 months, and at 6 months with subgroup analysis. The ability to detect differences is potentially reduced by intervention group reduction in medications, and a decrease in dietary adherence over time. HbA1c reductions favoured the intervention and all intervention patients with a diabetes diagnosis improved while adherent, and two resolved their condition by HbA1c. At 6 months, the intervention compared with the control had an increased quality of life, general and nutritional self-efficacy, and self-esteem, without significant changes in food enjoyment, cost or exercise. Total regular medication usage decreased in the intervention group and increased in the control group.

Reviews comparing the WFPB approach to other diets show similar weight loss at 12 months for low-carbohydrate and low-fat diet approaches. Individual studies that combine regular exercise with either unrestricted or energy-restricted low-carbohydrate diets have observed similar weight loss to our intervention at 6 months. However, studies on the effects of low-carbohydrate diets have shown higher rates of all-cause mortality, decreased peripheral flow-mediated dilation, worsening of coronary artery disease, and increased rates of constipation, headache, halitosis, muscle cramps, general weakness and rash. Other energy-restricted diets can be effective for weight loss. However, by restricting amount of food eaten, patients are likely to feel hungry, and hunger scores have been shown to predict those at risk of weight regain.