The BROAD (née Fraud) study is a perfect example of how misleading articles can get published, and how we an manipulate our findings to suit a narrative. Misleading, misrepresented and poorly designed studies are rampant, and unfortunately within the plant-based/vegan diet literature, it appears to be the more sensational the better.

I recently had to review this article for a college assignment, but I think it is perfect to run through and discuss some of the salient points from the article.

You can access the article here.

Introduction

Obesity is a global challenge, placing huge strain on the individual and society as a whole.

No denying that. Elevated BMI is associated with increased risk of cardiometabolic disease and a litany of other health problems. Again, no denying that.

There is at present, no “one diet” for successful weight loss for everyone.

This is also indisputable. Dietary intake and choices are influenced by a whole host of factors, ranging from education and affordability to downright availability. The authors also make the point that low-carbohydrate and low-fat diets have both been proven successful for weight loss. However, in both cases many overweight participants regain the weight back. Further adding weight to the claim that there is no one best diet that suits everyone. It is important to note this, as the authors later shoot themselves in the foot with this statement.

Enter our lord and saviour, the whole-food, plant-based diet (WFPBD).

She’s high in micronutrients. She’s low in fat. She’s ethical. She’s a sustainable queen. She has links with reducing cardiovascular disease, weight loss and even lowering prostate specific antigen (PSA) levels. Enter the panacea, Miss WFPBD.

Is there anything she can’t do? As per this propaganda, absolutely not! Does it matter that we are equating all of these benefits solely to whole-foods, and not to overall reduction in energy intake (which has also produced similar results)? Also absolutely not!

With our bias firmly evident, we now get into the study itself.

Subjects & Methods

Study participants are aged 37-70, obese or overweight with at least one of the following conditions: type II diabetes, chronic heart disease or hypertension/cardiovascular disease risk factors.

There is a vast exclusion criteria from the study – smoking, drugs, mental health issues affecting energy intake etc. This is exclusion criteria is one of the few strengths of the study – effort was made to limit the influence of confounding variables.

We divide our population into a control and intervention group.

The control group receive standard medical care.

The intervention group receive medical care and a vegan “diet change programme” (read: brainwashing). Now this is where we get to some tomfoolery.

The Intervention/Brainwash

The intervention group are instructed to follow a low-fat, plant-based diet (7-15% fat). They attend bi-weekly meetings for 12 weeks. It is painted as a lovely intervention, with group discussions, chef demonstrations, quizzes and even a potluck dinner. Vegan 4 life amirite guys?

Exit the holding hands and tree hugging, and subsequently, enter sensationalism and pseudoscience.

Participants were shown educational documentaries such as Fork Over Knives and received presentations from doctors.

Won’t someone please think of the scientific method? Have we gone so far past the realms of science that we are now considering a NETFLIX DOCUMENTARY appropriate for a medical intervention? What is peer-reviewed about that? And these “doctor presentations”. Who are the doctors? What is the nature of the presentations? For all we know, they could be saying anything not grounded in science (and it is most likely the case given we are screening Netflix documentaries).

Participants were given dietary advice, and a “traffic light” diet sheet, with foods to avoid completely, and to include more of.

OK. So, participants are told to eat bread and starches to satisfy their appetite. I wonder about the nocebo effect here. In addition, they are told to avoid refined oils, animal products, high-fat foods (god forbid you get some polyunsaturated fats in) and processed foods. In addition, intake of salt, sugar and caffeine is limited. Participants are provided with a B12 supplement. There are no restrictions placed on energy intake, and participants do not track their intake.

Results

BMI and cholesterol levels are the main focuses of the study. Secondary outcomes measured are: quality of life, medication use and risk of cardiovascular disease.

Overall, 65 people are involved in the study. Those following the plant-based diet decrease their BMI significantly more than the control group. Cholesterol levels are also more favourable in the intervention group, HOWEVER this is not significantly different to the control group.

The intervention group also report an improvement in CVD risk and quality of life.

So, this whole-food plant-based diet is amazing right?

From the results alone, it would appear we have struck dietary gold.

Discussion

Now, let’s breakdown some of the key points, and discuss why you can’t just report what supports your desired outcome.

The whole-food plant-based dieters lost weight, without restricting their intake, or increasing exercise.

Weren’t restricting their intake? Is this a joke? Please see the above for a list of all the food that was restricted. You are allowed literally fruit and vegetables. How is that not restrictive???

Weight loss comes from a calorie deficit, not the magic vegan fairies that enter your body through plants and hack away at your adipose tissue whilst you sleep.

Foods such as fruit and vegetables have a very low energy density, meaning that you would need to eat a hell of a lot of them to gain weight. Such foods increase satiety, which is beneficial in reducing energy intake. In addition, if all you could eat was broccoli, you’d lose weight by default, because who wants to eat that much salad all the time?

Whilst the amount of food wasn’t restricted, the type of food certainly was. It is not fair to conclude that there was no element of restriction in this study.

The intervention group successfully lost weight. It is hypothesized this was due to an increase in food volume. This satiety increase resulted in an overall lower calorie intake. However, with no food records we cannot be sure if this was true, or whether participants even followed the diet!

Whole-food plant-based diets lead to a reduction in cholesterol and more favourable health outcomes.

From this study, one could certainly conclude this. And, as this study shows, there are clearly health benefits from including whole-food, plant-based foods in the diet. This is undeniable! However, we can not attribute all the health benefits from the study solely to the elimination of animal products/fat in the diet.

Consider the Mediterranean diet, which incorporates animal products and oils. This diet has reported similar favourable alterations in metabolic profiles and health factors, all the while including *gasps* animal foods^[1]!

A variety of behaviour change techniques were used to guide the intervention.

A variety of techniques were employed by researchers, but not all of these techniques were appropriate.

Behavioural modelling and problem solving was effectively used. Involving participants in cooking classes to increase their knowledge and skills is widely accepted in literature as an effective method of altering dietary behaviour^[2]. In addition, improving knowledge/skills also promotes self-sufficiency amongst the individual. I have no beef (lol 10/10 pun) with teaching people necessary skills, and if it promotes health by all means off you go.

Social support was an appropriate technique that hugely assisted the success of the intervention. Creating a sense of identity and community amongst intervention participants was highly significant. This is hugely effective in literature as an effective predictor of dietary adherence in vegan/WFPBD^[3].

Provision of “traffic light” eating guides and screening “pro-vegan” documentaries may not be appropriate. By assigning a moral value to food, dichotomous thinking may be created amongst participants. Participants may feel guilt/shame over their dietary behaviour. This may be exacerbated if the diet is “broken” by consumption of “red/bad” foods. Amongst the overweight, guilt and shame can be detrimental to dietary adherence and self-efficacy^[4]. Have we not all read Bréne Brown in 2021? Shame does not equal success in the long-term.

Adherence decreased by 30% within the intervention group.

No reasons for this are given.

Could it be that whole-food, plant-based diets don’t cure everything? And there is no one diet fits all (as they mentioned in the introduction!).

Or is it possible that eliminating a huge majority of food groups is too drastic for many people? Who knows, we have no reason why!

Let’s Talk Bias

Of note, several researchers were shareholders in companies that profit from marketing plant-based lifestyles. This bias is evident in the reporting of results. Emphasis is placed on the success of the intervention in lowering BMI/improving health outcomes. Little focus is given to the fact that the blood pressure of the intervention group actually increased over the course of the study (it wasn’t statistically significant). Similarly, one participant in the intervention group underwent gallstone removal during the study. This is a common adverse effect from very low dietary fat intake^[5]. But let’s just gloss over that because it doesn’t fit our vegan narrative!

Conclusion

You would be forgiven for reading this and thinking I have it in for vegetables. No, a kale salad did not murder my entire family. I am not disputing the huge health benefits to including whole-food plant-based foods in your diet. Indeed, I think most people could benefit from including a lot more of them in their diet!

What I am disputing, is misleading and misreporting results. Giving too much credit where it is not due.

It is evident that reducing the intake of salt, sugar and highly processed foods offers many health benefits. Similarly, including whole-food plant-based foods in the diet can benefit the individual. These foods may encourage weight loss amongst overweight individuals as they are less energy dense than many processed animal-based foods. This increase in satiety may help adherence.

WFPBD is an effective intervention for weight loss, but adherence can be an issue, and the reasons for this are not detailed in this study.

The influence of social support and education in successfully altering dietary behaviour is evident.

I am curious to hear your thoughts on this paper – and please let me know if you have any criticism or feedback on this article. Always happy to discuss (and very much open to being wrong!).

References

1. Esposito, K., Kastorini, C.M., Panagiotakos, D.B., Giugliano, D. (2011) ‘Mediterranean Diet and Weight Loss: Meta-Analysis of Randomized Controlled Trials’, Metabolic Syndrome and Related Disorders, 9(1), pp. 1-12.
2. Hollywood, L., Surgenor, D., Reicks, M., McGowan, L., Lavelle, F., Spence, M. (2017) ‘Critical review of behaviour change techniques applied in intervention studies to improve cooking skills and food skills among adults’, Critical Reviews in Food Science and Nutrition, 58(17).
3. Cruwys, T., Norwood, R., Chachay, V.S., Ntontis, E., Sheffield, J. (2020) ‘”An Important Part of Who I am”: The Predictors of Dietary Adherence among Weight-Loss, Vegetarian, Vegan, Paleo and Gluten-Free Dietary Groups’, Nutrients, 12(4), pp. 970.
4. Thøgersen-Ntoumani, C., Dodos, L.A., Stenling, A., Ntoumanis, N. (2020) ‘Does self-compassion help to deal with dietary lapses among overweight and obese adults who pursue weight-loss goals?’, British Journal of Health Psychology, 1(1).
5. Erlinger, S. (2000) ‘Gallstones in obesity and weight loss’, European Journal of Gastroenterology & Hepatology, 12(12), pp. 1347-1352.