12 November 2023
Can botox injections to the calves give rise to slimmer legs? Yes it can; and this treatment is a trend in South Korea and China. The use of botox injections for body contouring is considered an off-label use of botulinum toxin; but its popularity has been growing steadily in Singapore and around the world. More recently, #TrapTox or trapezius botox for shoulder contouring has made a comeback in popularity, thanks to viral TikTok videos that have made TrapTox great again. Now, calf botox for slimmer legs has entered the chat once more; and the inspiration for this might come from the popularity of K-pop idols like Lisa from BlackPink, who are admired by fans for their long and slender legs.
Due to ethnic differences in calf shapes, Asians have short, ovoid legs; whereas Westerners tend to have long and slim legs1. In Korea and Asia, the appearance of shorter, thicker calves is colloquially called “radish legs” and are also considered to be less desirable1. Consequently, contouring of the calves for slimmer legs has become a highly sought-after treatment among Asian women2.
Some of the treatment options to reduce muscle bulk in the calves are liposuction, myectomy (partial resection of the calf muscles) and neurectomy (resection of nerves)1. However, the risks of these surgeries for slimmer legs; as well as the limitations of these surgeries have led to the search for a safer, reliable treatment option for reduction of the muscle bulk of the calves1.
Calf reduction botox refers to the introduction of Botulinum toxin injections into the calf muscles- specifically, the gastrocnemius muscles. The gastrocnemius muscle is a leg muscle at the back of the lower legs; and it accounts for most of the size of the lower legs when viewed from the back.
Botox or botulinum toxin affects the communication between nerves and muscles temporarily by inhibiting the release of a neurotransmitter called acetylcholine. By introducing botulinum toxin into the calf muscles (i.e. gastrocnemius muscles), the size of the calf muscles gradually reduces1,3,4. The reduction in size of the gastrocnemius muscles reduces the size and prominence of calf muscles when viewed from the back1,3,4.
What are the effects of long term Botox injections?
The slimming effect of the leg muscles is due to controlled atrophy of Botox on muscles. This is similar to the use of Botox to treat enlarged masseter muscles (jaw muscles) to relieve jaw aches and to slim down the appearance of the face5,6.
The causes of enlarged calf muscles are conditions with peripheral nerve lesions, chronic spinal atrophy, chronic recurrent polyneuropathy,and poliomyelitis17-10. In majority of cases of cosmetically enlarged gastrocnemius muscles, the cause is unknown3.
Botox injections to slim the calf muscles works for patients with bulky and muscular calves. Those with medical conditions that contribute to enlarged muscles (see above) will require specific treatment for these conditions.
In my clinic in Singapore, patients will first have to be evaluated during the consultation to identify the causes of their bulky calf muscles. Patients who have enlarged calves due to edema (swelling) or accumulation of fat will not benefit from Botox injections to the calf muscles.
Patients who are candidates for botox to the leg muscles for contouring of the calves will proceed with the treatment. First, The calves are numbed topically. After clinical documentation of the calf sizes, and marking out the injection points, Botox is next injected into the calf muscles. The injection sites of Botulinum toxin into the leg muscles are tailored to the individual’s anatomy.
There is some discomfort related to the injection of Botulinum toxin into the muscles.
Based on a review in 2020 of all available studies published on calf botox to contour the legs in East Asians, the reduction of the calf circumference in these studies ranged between 0.39 to 2.0 cm4.
It takes 4-6 weeks for the results of side effects of calf reduction botox for slimmer legs. The gastrocnemius muscle is a large muscle in the body, hence enough time must be given for the effects of Botox injections to the calf to be seen.
The reported side effects of botox injections to the legs include:
1) Calf muscle fatigue (when wearing high heeled shoes)1
2) Leg cramps that worsen with walking11
3) Muscle tiredness12
4) Temporary bruising4
The results of Botox injections to the calm muscles for slimmer legs lasts 4-6 months. The results of Botox injections are not permanent.
Alternatives for slimming down the calf are non-surgical fat removal (e.g. fat freezing) liposuction, neurectomy (nerve ablation or resection) and myectomy (surgical resection of the calf muscles).
Botox for body contouring, especially of the calves, has emerged in the last 20 years as a non-surgical; and minimally invasive therapy for hypertrophic muscles. The premise of Botox injections to slim down these muscles is controlled atrophy; similar to TrapTox or trapezius muscle botox injections for shoulder slimming.
Fat removal, by non-surgical methods such as fat freezing, is more useful in scenarios where the patients has fats contributing to the bulk of the calves.
1. Botulinum toxin A treatment for contouring of the lower leg. Han et al. J Dermatolog Treat. 2006;17(4):250-4.
2. Some Korean Women Are Taking Great Strides to Show a Little Leg. Schuman. The Wall Street Journal 2001; Feb 21.
3. Botulinum toxin a for aesthetic contouring of enlarged medial gastrocnemius muscle. Lee et al. Dermatol Surg. 2004 Jun;30(6):867-71; discussion 871.
4. Botulinum Toxin Injections for Leg Contouring in East Asians. Cheng et al. Dermatol Surg. 2020 Oct;46 Suppl 1:S62-S70.
5. Type A botulinum toxin for the treatment of hypertrophy of the masseter and temporal muscles: an alternative treatment. von Lindern et al. Plast Reconstr Surg. 2001 Feb;107(2):327-32.
6. The medical management of masseteric hypertrophy with botulinum toxin. Finn et al. J Ir Dent Assoc. 2000;46(3):84-6.
7. Muscle hypertrophy with neuropathy. Korczyn et al. J Neurol Sci. 1978 Oct;38(3):399-408.
8. Anterior-horn cell degeneration and gross calf hypertrophy with adolescent onset: a new spinal muscular atrophy syndrome. Pearn and Hudgson. Lancet. 1978 May 20;1(8073):1059-61.
9. Myokymia, muscle hypertrophy and percussion ‘myotonia’ in chronic recurrent polyneuropathy. Valenstein et al. Neurology. 1978 Nov;28(11):1130-4.
10. Postpoliomyelitis muscle pseudohypertrophy. Bertorini and Igarashi. Muscle Nerve. 1985 Oct;8(8):644-9.
11. Treatment of Gastrocnemius Muscle Hypertrophy with Botulinum Toxin Injection Followed by Magnetic Resonance Imaging Assessment and 3-Dimensional Evaluation. Bogari et al. Aesthet Surg J. 2017 Oct 16;37(10):1146-1156.
12. A pilot study comparing the efficacy of two formulations of botulinum toxin type A for muscular calves contouring. Wanitphakdeedecha et al. J Cosmet Dermatol. 2018 Dec;17(6):984-990.