Can a high protein diet cause abnormal menstrual cycles?

High Protein Diets and Menstrual Cycle Abnormalities

High protein diets may potentially cause abnormal menstrual cycles, particularly when they lead to significant caloric restriction, rapid weight loss, or nutritional imbalances that affect hormonal regulation.

Impact of High Protein Diets on Menstrual Function

• High protein diets, especially those that severely restrict carbohydrates, can disrupt normal menstrual patterns by creating hormonal imbalances 1
• Rapid weight loss from restrictive high protein diets can lead to menstrual cycle disruptions, with some women experiencing irregular cycles for 3-6 months after dieting 2
• The American Heart Association does not recommend high-protein diets (≥20% of total energy) or very-high-protein diets (≥30% of total energy) for weight reduction due to potential health risks 3

Mechanisms of Menstrual Disruption

• Caloric restriction associated with high protein diets can interfere with gonadal steroid production, causing menstrual disturbances even without suppressing luteinizing hormone (LH) secretion 2
• Diets with inadequate energy availability can lead to relative energy deficiency, which is known to disrupt normal menstrual patterns, particularly in athletes 4
• Low intake of vegetable protein has been associated with lower luteal phase progesterone, higher follicle-stimulating hormone, and a higher risk of anovulation compared to moderate intake 5

Nutritional Balance and Menstrual Health

• Female athletes should aim for energy availability of 45 kcal·kg–1 fat-free mass·day–1 for optimal health and menstrual function 3
• Micronutrient requirements and hydration needs may change during various phases of the menstrual cycle due to hormonal fluctuations 3
• Protein intake should be proportional (approximately 15% of calories) to carbohydrate (approximately 55% of calories) and fat (approximately 30% of calories) intake for optimal health 1

Common Pitfalls and Recommendations

• Severely restricting carbohydrates while increasing protein can exacerbate acid load and lead to nutritional deficiencies that may affect reproductive health 1
• For individuals with diabetes and normal renal function, there is insufficient evidence to suggest that usual protein intake (15–20% of energy) should be modified 3
• High-protein diets are not recommended as a method for weight loss as the long-term effects of protein intake >20% of calories on health complications are unknown 3
• Diets high in fruits, vegetables, and whole grains provide essential nutrients like potassium, magnesium, and calcium that support overall health, including reproductive function 1

Monitoring and Prevention

• Women on high protein diets should monitor their menstrual cycles for irregularities, as these may be early indicators of hormonal disruption 4
• Ensuring adequate total caloric intake and balanced macronutrient distribution is crucial for maintaining normal menstrual function, even when following a higher protein diet 3
• Protein from diverse sources, including both animal and plant proteins, may help prevent the negative impacts on ovulatory function seen with very low vegetable protein intake 5