Dr. Tamsin Lewis: Dangers of Ketogenic and Low-Carb Diets, and Why Females Are Higher Risk

January 1, 2016
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We are joined by Dr. Tamsin Lewis, who’s become a new mom since her last appearance on EP! Read Tamsin’s pregnancy blog, mentioned on the show. You can hire Tamsin for a health consultation at Curoseven.com.

This episode investigates the risks and dangers of going to low carb, and advises athletes to assess their health via blood tests, consulting with professionals, etc, before taking on any extreme diets. 

1. What are the risks of going too low carb or keto; problems you can create with these diets?
2. Who should avoid extreme low carb and ketosis (<50g/day)?
3. Take home: Finding health, finding balance

Defining ketosis

  • – similar to starvation mode
    – use mainly fat and protein for energy
    – eating <50 g CHO/day
    – exogenous forms of ketones

What are the potential risks of going too low carb or keto; problems you can create with these diets?

  • Gastrointestinal issues
    – constipation, diarrhea, pain, bloating, etc
    – disrupting the microbiota, epigenetics, and is keto the preferred diet for you?
  • Female specific issues
    – problematic for supporting a healthy female hormone environment (disruption; depletion)
    – high cortisol & the pregnenalone steal
    – signal that body is in high stress state
    – can create thyroid problems
    – TSH increase; T3, T4 decrease
    – cortisol up, progesterone down; menstrual irregularities
    – potential loss of cycle or irregular period with too low carb
    – importance of diet during the luteal phase
    – psychological issues; anxiety and depression
    – caloric restriction/low-calorie mistakes
    – infertility and pregnancy complications
    – anecdotal evidence of: low-carb great at first, weight loss, etc, then you crash and hormones go crazy, get depleted, etc
  • Can males suffer from similar hormonal and health issues as females?
    – testosterone disruption (the fight with cortisol)
    – muscle loss
    – catabolic vs anabolic states
  • Athletes:
    – trouble recovering
    – trouble reaching high-end speed/intensity
    – trouble executing training (volume and or intensity)
    – trouble if overtrained
  • Glucose & cholesterol issues
    – if you have high fasting blood glucose and cholesterol circulating in blood stream
    – a weird thing can happen: switching to LCHF = increase in fasting BG
    – the brain induces insulin resistance to preserve glucose for itself
  • Keto and LC foods: beware of artificial foods, dairy, fewer veggies
    – a lot of keto recipes call for stevia and artificial sweeteners to avoid sugar, bad news
    – a lot of dairy recipes too
    – “bacon salad syndrome” – protein and fat but not enough veggies
    – missing variety of nutrients

Other options for fat-adaptation

  • Metabolic flexibility
    – carb timing, use carbs as a weapon for training/racing
  • Example: Zach Bitter
  • Thoughts on high carb

So, who should avoid/consider avoiding:
(or get healthy first)

  • Thyroid problems, hypothyroid
    – TSH, T3, T4
  • Females who exhibit:
    – triad cases
    – who tried to be healthy actually got very sick and compromised; until the underlying issues are solved NK is not going to work well and even backfire
    – hypothalamic amenorrhea, eating disorder, energy availability
    – body too chronically in sympathetic state
    – mention of the “high” that comes with ED, keto
    – active athletes
    – trying to increase fertility or currently pregnant
  • Adrenal fatigue or other hormonal imbalance
  • Other underlying conditions, disease or metabolic issues (diabetes, cholesterol issues, etc)
  • extreme training; endurance or HIIT
    – can slip in and out of keto/low carb but still in need of carb refuel/moderate carbs

Who has success with keto?

  • Sufficient calorie intake. eat enough calories! Eat fat like it’s your job!
  • Cyclic approach
  • Metabolically fit, healthy people
  • Using carbs when they are needed for sports performance!

Take home & finding the balance

  • We are still seeking health, wanting to avoid refined carbs, sugar, maintain steady energy, be metabolically efficient, etc. So avoiding LC/keto is not a pass to eat high carb junk foods. It’s about moderate carb intake
  • 50-60% fat, 20-30% protein, 10-30% carbohydrate?
    – seems like 100-200g CHO/day is safe for most
    – or more traditional 40-50% CHO may work, it depends
    – carb cycling
  • Make it your goal to get metabolically fit and solve your underlying health conditions. so whether you choose keto or not as your diet you at least know you are a healthy individual.

More Resources:

The Paleo Mom – List of Keto Dangers
Robb Wolf – Females, Carbohydrates, and Hormones 
Paleo for Women – the Pregnenalone Steal
Chris Kresser – is a low-carb diet ruining your health?
TriTawn – Quitting gum

Comments (3)

  • r3rameysrandomrambli says:

    You mentioned in the intro but I didn't catch it during the chat about protein raising BG also. I shoot for somewhere around 40C/30-35F/30-35P but still have a higher BG in the AM. Just unsure where to move the %'s (maybe more fat?!?) Love the podcast and the wealth of info you share.

  • vegpedlr says:

    This was more interesting than I thought. Considering the discussion, I don't know what is so attractive about a LC diet. Especially the long term unknowns, which is why I'm happy with my traditional starch based diet modeled after the Kenyans, Tarahumara, and Okinawans.

  • TW_EnjoyAllLife says:

    Your discussion was SO interesting and what I've been dealing with the past 4 years! I'm currently going through test after test showing thyroid issues/parathyroid/pituitary issues. I'm really beginning to think what I thought was healthy eating (veggies, low carbs, little fat), lack of sleep and push to stay as active as I could possibly be has disrupted SO many things in my body and you mentioned MANY of them! Love your all your great information! Thank you!


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