Snacking is not always unhealthy, but it all comes down to what you choose to munch on between meals. According to a study, unhealthy snacking can counteract the benefits of a healthy meal, and the timing of your snacks can be a crucial factor.

A team of researchers from the School of Life Course and Population Sciences, at King's College London and ZOE – a personalized nutrition program in London – found that unhealthy snacking can raise the risk of stroke and cardiovascular diseases. Snacking after 9 p.m. was linked to blood markers associated with poor health. The findings of the study were published in the European Journal of Nutrition.

The team evaluated the snacking habits of 854 people from the ZOE PREDICT study, an in-depth nutritional research. Around 95% of people had snacking habits, out of which 47% ate two snacks a day and 29% ate more than two.

Around 26% ate healthy main meals but took poor-quality snacks. Most of the participants opted for snacks like cookies, fruit, nuts and seeds, cheese and butter, cakes and pies, and granola or cereal bars.

Researchers found the act of snacking in itself is not harmful, but by having snacks high in fat and sugar, the positive effects of healthy meals are canceled out.

Replacing confectionaries, processed food and sweetened drinks with nutritious snacks such as whole fresh fruit and vegetables, nuts and seeds can help improve cardiometabolic health and glycaemic control and reduce appetite.

"Considering 95% of us snack, and that nearly a quarter of our calories come from snacks, swapping unhealthy snacks such as cookies, crisps and cakes to healthy snacks like fruit and nuts is a really simple way to improve your health," study author Dr. Sarah Berry said.

Those who snacked late at night, after 9 p.m., tend to opt for high-fat and high-sugar snacks. These energy-rich food items were linked to poorer blood indicators when they were compared to the snacks taken at other times.

"This study contributes to the existing literature that food quality is the driving factor in positive health outcomes from food. Making sure we eat a balanced diet of fruit, vegetables, protein and legumes is the best way to improve your health," said Dr. Kate Bermingham, another study author.