Having too little protein in your diet can lead to a number of issues, including:

Increased sugar cravings
Hunger
Weakness and fatigue
Loss of muscle mass
Thyroid imbalance
Impaired immune system (think: injuries take longer to heal)
Decrease in growth hormone and oestrogen (which can also lead to hair thinning or falling out, fading hair colour and brittle nails)

Batt explains that a protein deficiency can contribute to several issues, including anaemia, which is most commonly caused by a lack of iron in the diet. Having periods is one of the most common causes of iron deficiency, as blood loss leads to a loss in iron-rich red blood cells: around 14% of people who menstruate are thought to suffer from anaemia related to low iron levels, according to the National Institute for Healthcare Excellence. Work out regularly? Then you might be more at risk: about 15-35% of female athletes have iron deficiency, compared to about 5-11% of male athletes, according to a 2019 review.

Veganuary 2023: how to make sure you’re getting enough protein on a vegan diet