With comfort eating becoming a preoccupation for individuals during lockdown, CONNECTED speaks to University of Reading experts about the myths surrounding appetite-suppressing foods and COVID-19 ‘miracle’ foods.
Fuller for longer?
There are plenty of foods and protein drinks that are marketed with the promise to keep hunger at bay. Foods are often developed with the aim of increasing satiety or satiation, but what exactly is meant by these terms? CONNECTED speaks to nutritional scientist, Dr Miriam Clegg, from Reading’s Department of Food and Nutritional Sciences to find out more:
“Appetite is our desire to eat. And while hunger is a cue from our body, appetite is a cue from our brain. Satiety and satiation are often used interchangeably in relation to appetite but actually have different meanings.
“Satiation is the process that leads us to stop eating, whereas satiety is the feeling of fullness that persists after eating, potentially suppressing further energy intake until hunger returns. In simple terms, what makes us put down our knife and fork is satiation, and what keeps us from starting our next snack or meal is satiety.”
As Dr Clegg highlights, despite sophisticated mechanisms in the body to control food intake, people often still eat when they feel satiated or resist eating when hungry. There are many factors that influence eating behaviour as well, such as portion size, tastiness and emotional state.
With many Britons constantly trying to lose weight, the floodgates have opened for fad dieting and the marketing of appetite-supressing products which can be dangerous. Dr Clegg said:
“Currently, there is limited evidence to support the effect of satiating foods in obtaining a healthy body weight. But many food and supplement brands still appear to advertise the benefits of suppressing appetite regardless of health claim regulations – particularly outside the EU. A prime example is the Flat Tummy Co’s ‘appetite-supressing’ lollipops which are marketed to maximise satiety, but in terms of evidence there is no robust science to support these claims. This is because there is insufficient evidence characterising appetite and weight, with most studies focusing on one or two days’ effects.”
When is increasing appetite important?
Much focus goes into decreasing appetites, but appetite research is also concerned with increasing appetites, for example, in older people who report having a diminished appetite for a variety of reasons. Dr Clegg explains:
“These reasons may include physical factors such as slower emptying of food from the stomach, and social factors such as bereavement, depression or isolation. Reduced physical function, sight, smell and taste impairments, medication and dental problems can all influence appetite.
“The elderly usually eat less than younger people. They experience fewer hunger pangs and satiation at meals is faster. Together, these factors can result in a reduction in appetite and a reduced desire to buy and prepare food, which affects their nutritional health.
“In this group, foods that promote appetite and encourage increased food intake are required to prevent malnutrition.
“Another challenge for older people is that the type of foods they require need to be good sources of protein. Protein is considered to be the most satiating nutrient, but it can increase mouth drying and, if it is meat-based, may require longer chewing, which makes it difficult to consume. Much is still unknown about appetite responses in older people, and more research is needed to explore how appetite can be increased in this population.”
As it stands, there is convincing evidence for the short-term satiating effects of some foods and nutrients, but much less evidence on the longer-term impact of these foods on weight control. Dr Clegg argues that more studies specifically designed to demonstrate a causal link, if any, between appetite and weight control are needed.
COVID-19 food myths
Not only have myths surrounding appetite-suppressing foods become more prominent, but so have myths surrounding so-called ‘miracle’ foods that can prevent or cure COVID-19. Even though the World Health Organization (WHO) has tried to dispel such myths, misinformation continues to circulate on social media. As dietitian and Reading PhD researcher – Taibat Ibitoye – highlights, there is currently no evidence that eating certain foods or following certain diets will protect us from COVID-19.
Taibat tells CONNECTED of the food myths that need to be debunked:
Myth 1: Garlic
There is some evidence showing that garlic has antibacterial effects, with existing studies indicating the active compounds of garlic are protective against some types of bacteria like salmonella and staphylococcus aureus. However, research investigating garlic’s antiviral properties is limited.
“Though garlic is considered to be a healthy food, there’s no evidence showing that eating it can prevent or cure COVID-19.”
Myth 2: Lemons
One viral Facebook video claimed that drinking warm water with lemon slices could combat COVID-19. However, there’s no scientific evidence that lemon can cure the disease.
“Lemon is a good source of vitamin C, which is important for helping immune cells work properly, however, many other citrus fruits and vegetables contain vitamin C.”
Myth 3: Vitamin C
Vitamin C is known to play a role in supporting the normal functioning of the immune system. Yet, it’s not the only nutrient that maintains the immune system.
“Most of the misinformation on vitamin C and COVID-19 comes from studies that have investigated the links between vitamin C and the common cold. Despite claims online that vitamin C can prevent and treat the common cold, the evidence in support of this is not only limited, but conflicting too. There are also significant differences between the common cold and coronavirus.”
There is currently no strong evidence that supplementing diets with vitamin C will prevent or cure COVID-19.
Myth 4: Alkaline foods
“Misinformation spread on social media suggests the virus can be cured by eating foods with a pH [level of acidity] that is higher than the virus’s pH. Some of the ‘alkaline foods’ said to ‘cure’ COVID-19 are lemons, limes, oranges, turmeric tea and avocados. However, many of these online sources give incorrect pH values to these foods.”
Overall, there’s no evidence indicating that foods can even affect the pH levels of blood, cells or tissues – let alone cure viral infections.
Myth 5: The keto diet
The ketogenic (keto) diet, which is a high-fat and low-carbohydrate diet, has been said to be protective against COVID-19.
This comes from the idea that it can ‘boost’ the immune system. Though one study showed that keto might prevent or treat the flu, this study used mice models. This makes it difficult to know if keto would have a similar effect on humans at preventing or treating the flu.
“There is also currently no existing scientific evidence demonstrating that a ketogenic diet can prevent coronavirus.”
In fact, the British Dietetic Association (BDA) has stated no specific food or supplements can prevent a person from catching COVID-19. Alongside the WHO, they encourage people to consume a healthy, balanced diet that contains the five main food groups to support the immune system.
People are also encouraged to take protective measures against COVID-19, including washing hands frequently, maintaining social distancing and following lockdown orders.
Social media is a powerful tool, however, it can also be a catalyst for spreading misinformation. The bottom line is that there are no miracle foods or supplements guaranteed to protect people from COVID-19.
These articles were first published in The Conversation on 1 April 2020 and 21 April 2020.