“I’d love for women to get really clear information that’s based on the evidence because we have been misled … throughout history,” Black told the Herald.
The researcher and lecturer said she became motivated to carry out the research after friends, clients and athletes started expressing ideas that didn’t sound correct.
“[They were] telling us they had to do X, Y or Z around exercise in terms of their nutrition or it would be unhealthy, they weren’t maximising their training.”
The prevalence of claims that lack robust evidence is confusing women, said Black.
She had never heard of some of the claims she came across, and had to look them up.
“I was like, well, I’ve got a PhD, I’m a professor in nutrition. If it’s something I have to go and look up and really research, then for the layperson who isn’t in this field, I imagine it’s really confusing.”
Myth 1 – Women should not train fasted
Some social media posts seen by Black claimed that if women exercise on an empty stomach (fasted training), their metabolic markers, hormones, reproductive health and metabolism would be negatively impacted. They also claim it can cause belly fat.
For Black, this plays on women’s vulnerabilities around body image, “particularly adolescent girls and [women around the age of] menopause, perimenopause – the two biggest groups where we’ve got eating disorders and body image issues”, she said.
Well-cited research papers behind the claim come from studies on rodents, but they do not “fully translate to human research”, Black said.
Black acknowledged research on humans is limited, but she said existing findings show it doesn’t matter if one trains fasted or fed.
The study concluded women are unlikely to suffer significant adverse effects if they have a healthy calorie intake.
Myth 2 – Periods influence how much a woman needs to drink
Social media posts have claimed hormone changes during the menstrual cycle shape how much women need to drink while working out, and that dehydration was more likely when hormone levels were peaking as a result of changes in body temperature and sweat response.
Black said hydration needs during exercise are “very different from individual to individual”.
It should be based on how much they sweat, the unique environmental conditions and how long they plan to work out, rather than the sex of the person or where a woman is in their menstrual cycle, Black’s study noted.
She suggested drinking to thirst for most training, and adjusting fluid and electrolyte intake based on heat, effort and personal sweat rate.
Myth 3 – Carbohydrate needs differ between men and women or between phases of the menstrual cycle
Some on social media suggest whether someone is a man or a woman is a significant factor in how much carbohydrate their body needs. Another variable is where a woman is on their menstrual cycle.
However, Black said the body of evidence doesn’t support the claim from a physiological point of view.
According to Black’s research, it’s difficult to say carbohydrate needs differ solely on whether someone is a man or a woman, as there are also unique differences in an individual’s training status, fitness levels and body composition.
Myth 4 – Women should eat more protein before and after exercise
Another claim circulating online is that women should eat more protein before exercising. According to the claims, this helps stabilise blood glucose, reduces muscle breakdown during the workout, lifts metabolism post-workout and helps with sleep.
Some posts also claim eating protein within 30-45 minutes after a workout is better for muscle repair and growth because a woman’s metabolism is thought to return to normal levels faster than men’s.
“Prioritise achieving total daily protein targets and distributing intake evenly across meals; nutrient timing is only required when athletes train multiple times per day,” the study noted.
“Having protein soon after training may be helpful, but is not critical for most people.”
Why active women are targeted
According to Black, it is often stated online that there is no research on women’s health. Black said that is “not true” – and the view can make active women more of a target for misleading content online.
“That’s a really good hook to get women in: ‘Oh, we’ve been totally overlooked, but here’s something specifically for you’,” she explained.
The study stated there is some research on women, although it’s limited. According to its authors, much of the existing research to date has not measured menstrual status or confirmed the phase of the menstrual cycle via hormonal testing, for example.
The prevalence of false information highlights the broader challenge to address research gaps in women’s health, including how to keep adolescent girls and perimenopausal women involved in activity and sport, Black said.
While it’s positive that women’s health is getting more exposure online, she stressed “there has to be some actual research behind it”.
It can be difficult for people to identify credible content on social media because the way content is packaged “comes across as so convincing as if it’s evidence-based”, she said.
Black said she would be sceptical if the claim on social media lacked specific context.
“If [the content says] ‘women should’ and doesn’t say ‘active women’ or ‘elite athletes’ or ‘X, Y and Z type of women’, then probably have a bigger dive into it and see ‘well actually what does the evidence say for my situation?’”
The importance of individual context
What’s more important when working with a client is considering the context of the individual and their needs, not their sex.
“You look at the individual – what are their goals, what’s their health situation, why are they exercising? All of these things would probably give us a bigger picture of their nutritional needs than whether they were male or female.”
For example, an elite athlete training for performance might need to be more nuanced in the timing of food consumption and the amount they’re eating, while someone else who’s “just exercising for health” doesn’t need as many rules.
Instead of social media, Black recommended consulting a registered nutritionist or dietitian with an interest in exercise as the best place for individual advice.
Following the Ministry of Health’s physical activity and nutrition guidelines is a good place to start, she said.
Varsha Anjali is a journalist in the lifestyle team at the Herald. She is based in Auckland.