I’ve been a voice actor since 2004 and I’ve been on a low carbohydrate, high fat diet (LCHF) since April 10th, 2017. Over the past 9 months I’ve lost 86 lbs (down from 270 lbs to 184 lbs). I’d like to tell you about my experience regarding my vocal performance and health while on this type of diet.

I have received several requests, informally on reddit and formally from some of my clients, to write about anything I’ve noticed with my voice due to being on a high fat diet. I was extremely curious to see if there had been any changes at all with my voice, so I figured it was worth a little investigation.

I can only provide you with anecdotal evidence and my own experiences, so going into the details about the modified ketogenic diet I was using is beyond the scope of this analysis. (I’m not a doctor nor a nutritionist and I highly suggest you seek out a doctor should you have any questions about this type of diet). A great place to start is the /r/keto sidebar.

While eating this way, you get the majority of your energy from dietary fat. To allow my body to get into a state called nutritional ketosis, I had to limit my carbohydrate intake to no more than 20 grams per day. (Some people can enter ketosis with a slightly higher amount), but I decided to stay at 20 grams per day as that best fit my lifestyle.

By limiting my carbohydrate intake to 20 grams, it took about 7 days for my body to become used to not consuming sugars, or more accurately, carbohydrates. During the first 10-12 days I went through a phase called the “keto flu” where you can become dehydrated, can experience some muscle cramping and get headaches. This was like entering a type of mild withdrawal and it was not fun.

This was completely avoidable, but because of my inexperience and naivete on all things nutrition, I could have minimized this effect by performing more research and increasing my electrolyte intake. I could have also hydrated more efficiently. So basically, I had to suffer through it.

TYPICAL MEALS WHEN I STARTED:

For breakfast: 3 eggs [scrambled] + 2 tbsp heavy whipping cream and 1 oz grass fed butter. Paired with 2-3 oz cooked bacon and water or coffee plus Stevia and more cream. (Occasionally I would also have 1 oz of shredded cheddar cheese).
Lunch: 2 cups chopped romaine lettuce with 1-2 tbsp of mayonnaise, ¼ lb of 80/20 grass fed ground beef which was cooked in 1 tbsp of bacon fat. I would also add 3 oz of bacon if I were feeling exceptionally hungry, plus 1 liter of water
Dinner usually focused on either 4-8 oz of sirloin, ribeye or other fatty cut of steak, 1-½ cups of steamed (frozen) broccoli with 1-2 tbsp of grass fed butter, 1 liter of water and dare I say... more bacon!

VOICE ANALYSIS

During this initial ketogenic phase I noticed my voice was becoming “rougher” or more “dry” sounding. I don’t want to say it became more gravelly (since it’s always been a little rough) but there was a noticeable change (at least to my ears) during this "keto-flu"phase.

I performed a frequency analysis on some previous recordings and compared my findings to a voice recording done while in this initial ketogenic state. (I had tested my blood and urine to verify I was producing ketone bodies and that I had at least entered the beginning stages of nutritional ketosis).

During my research I found that some frequencies in my voice were “missing” or at the very least, affected by this diet. I saw a noticeable change in some frequencies between 4k-8k hz. This frequency range is where the typical human vocal sound of "ESS" lives. (The sound you make when you hiss like a snake). This sibilant sound, as it's known, can be a little harsh on the ears, so any reduction of it, was welcome.

The image represents only clean, unprocessed audio recorded directly to my audio workstation which was Adobe Audition CC 2017. The green "waveform" is a simple amplitude measurement of the sounds I made during recording. The red, yellow and purple display on the bottom of the editor show both amplitude and frequency. The vertical axis show's a frequency range of 20hz to just over 20khz. (Think of it this way; the "brighter" the "color" (like yellow) the louder the sound.

I recorded a narration track about the Harlem Hellfighters of WWI for Simple History (a fantastic YouTube channel), on March 18th, 2017 using a Neumann TLM102 through a balanced Mogami Gold cable into my Scarlett 2i2 as a mono track. (Shown as the right channel in amplitude statistics).

I then recorded a narration about the Great Pyramid at Giza, again for Simple History on April 16th, 2017. Six days after starting the ketogenic diet. Same signal chain; Neumann TLM102 through the same Mogami Gold cable and into the Scarlett 2i2 as a mono track. Shown as the left channel in amplitude statistics.

Visit the original blog post to hear the audio

RESULTS:

Although the highlighted area appears visually similar, there is a noticeable change in the frequency range of 4-10k. As well as more dynamic range in some of the higher sibilant frequencies.

Some of my sibilant transients seem to be augmented in this frequency range which I assign to having a “wetter” mouth due to entering nutritional ketosis.
The higher fat and dairy I consumed definitely contributed to more mouth noise and clicks.
There is also a brighter sound to my voice which seems to be a result of transient harmonic frequencies above 14khz.

I chose these two narrations due to their very similar delivery style and overall amplitude similarities. There is only one other noticeable difference in the spectral view; there seems to be a low end hum around 80 hz (no greater than -57db in amplitude) in the right channel sample, which I can attribute to my heating system.

CONCLUSION:

Although this is not a truly scientific experiment and it's only useful as an examination of possible physiological effects while on LCHF, it proved valuable to me as an artist to confirm some changes I was hearing in my own voice.

It appears that beginning a modified ketogenic diet has very little impact on your voice timbre or tone. However, there does seem to be some minor changes in some higher vocal frequencies; possibly sibilant harmonics above 14khz.

Due to the increased fat and dairy consumption that I performed, mouth noise increased. But with proper hydration and pre-session "mouth-maintenance", you can minimize this effect.

WHAT'S NEXT?

I will be continuing these experiments during my upcoming transition into an intermittent fasting state to validate any changes that might occur to my voice.

I would also like to add that I've had nothing but an amazing experience on this diet and would definitely recommend it to people who are interested in losing a large amount of weight in a short period of time. (Consult your doctor first, and by all means start reading the /r/keto threads and sidebar).

If you’d like to download this stereo file and perform your own analysis, feel free to do so. I would love to hear from anyone else with similar experiences! I’m afraid I can only provide the .mp3 version of this analysis, but if you’d like the uncompressed wav file just reach out to me.