By Tamzyn Murphy (RD)

Some people are concerned that an LCHF (low carbohydrate high fat) diet may not be appropriate for women at certain ages or stages of their cycle. Let’s take a closer look at whether there’s any basis to these concerns…

What we know… At all stages, fat and cholesterol are needed for sex-hormone production and fertility. Conversely, at no stage does carbohydrate become essential. Traditional populations who have followed ketogenic diets (KD) and maintained fertility (i.e. they haven’t died out), are testament to the fact that ketogenic diets can be followed without preventing fertility (e.g. Inuit and Masai populations). Whether there was a marginally negative impact of LCHF diet on fertility in these populations (i.e. would they have been more fertile following a higher carbohydrate, lower fat diet?), we can’t know.

What we don’t know… Despite the fact that there was no apparent negative impact of an LCHF diet on women in traditionally LCHF diet-eating populations, every woman is different, and some may find higher (up to 130 g/day) or lower (around 20 g/day) carbohydrate intakes (within the LCHF carbohydrate-intake-spectrum) more sustainable and suitable for them, in general and/or at different time of their cycle. This is absolutely fine, unless a specific therapeutic aim necessitates a specific level of carbohydrate intake. A healthcare professional with knowledge and training in LCHF diets can help guide women in finding the optimal daily carbohydrate intake for them or applying a LCHF diet for therapeutic purposes.

LCHF for reproductive health and fertility… depends on the woman, and her weight…

There is a growing body of evidence for improved fertility in overweight and obese women with/without polycystic ovarian syndrome (PCOS) who follow a KD [1, 2]. In these women, the KD is usually lower in energy and associated with weight loss. Making it difficult to determine whether the cause of the improved fertility associated with the LCHF diet is due to the diet per se, or the associated weight loss. Either way, the end result is improved fertility.

Conversely, however, in women who are normal weight and restrict energy intake to below 30 kcal/kg body weight [3], or reduce their body weight below their ideal (normal) range [4-6] a KD associated with reduced energy intake (or any other low energy or weight loss diet for that matter) can indeed be deleterious to reproductive health and fertility (e.g. lowering gonadotropin-releasing hormone, Luteinising hormone, and even precipitating amenorrhoea). However, this is due to the reduced energy intake and weight loss to below-weight recommendations, rather than any intrinsic property of the KD.

LCHF in peri- and post- menopause

People, particularly women, get more insulin resistant (IR) as they age [7]. So, if anything, a LCHF diet (known to be particularly effective for IR conditions [8]) becomes more indicated and effective as women transition into peri- and post- menopause.

Take home message

Women of any age and weight can likely follow an LCHF diet or KD. However, certain women stand to benefit more, specifically women with IR, i.e.:

• Overweight and obese women
• Women with PCOS (with the added possibility of improved fertility)
• Peri- and post- menopausal women

Whereas normal and low-weight women can follow an LCHF diet or KD but shouldn’t reduce their energy intake or lose weight while following the diet, or their fertility may be impacted negatively.

Enrol in one of the Nutrition Network online trainings and have your  questions answered by our LCHF experts. For more information about the trainings we offer, click here.

References

1. McGrice, M. and J. Porter, The effect of low carbohydrate diets on fertility hormones and outcomes in overweight and obese women: a systematic review. Nutrients, 2017. 9(3): p. 204.
2. Mavropoulos, J.C., et al., The effects of a low-carbohydrate, ketogenic diet on the polycystic ovary syndrome: A pilot study. Nutrition & Metabolism, 2005. 2(1): p. 35.
3. Loucks, A.B. and J.R. Thuma, Luteinizing Hormone Pulsatility Is Disrupted at a Threshold of Energy Availability in Regularly Menstruating Women. The Journal of Clinical Endocrinology & Metabolism, 2003. 88(1): p. 297-311.
4. Mady, M.A., et al., The ketogenic diet: adolescents can do it, too. Epilepsia, 2003. 44(6): p. 847-51.
5. Meczekalski, B., et al., Functional hypothalamic amenorrhea and its influence on women’s health. Journal of endocrinological investigation, 2014. 37(11): p. 1049-1056.
6. Alwahab, U.A., K.M. Pantalone, and B. Burguera, A ketogenic diet may restore fertility in women with polycystic ovary syndrome: a case series. AACE Clinical Case Reports, 2018. 4(5): p. e427-e431.
7. Yan, F., et al., Association of the number of years since menopause with metabolic syndrome and insulin resistance in Chinese urban women. Journal of Women’s Health, 2015. 24(10): p. 843-848.
8. Reaven, G.M., The insulin resistance syndrome: definition and dietary approaches to treatment. Annu. Rev. Nutr., 2005. 25: p. 391-406.