What are the risks of using weight loss shots in a patient with a normal Body Mass Index (BMI) of 23, an absent menstrual cycle due to an Intrauterine Device (IUD), and potential risk of osteoporosis?

Weight Loss Medications Are Contraindicated in Your Situation

You should not use weight loss shots with a BMI of 23, as they pose significant risks to your bone health through mechanisms that are independent of your IUD-related amenorrhea. The combination of intentional weight loss from a normal BMI and the metabolic effects of these medications creates a dangerous scenario for osteoporosis development.

Why Weight Loss Medications Are Dangerous at Your Current Weight

Your BMI Already Places You at Risk

• Women with low BMI (<25) have significantly increased osteoporosis risk, with each 1-unit decrease in BMI increasing bone loss risk by 12% 1
• At BMI 23, you are already in a vulnerable range where further weight loss would move you into the high-risk category (BMI <20) 1
• Low body weight is one of the strongest modifiable risk factors for osteoporosis, with greater magnitude of effect than most other interventions 1

Weight Loss Creates Energy Deficiency That Directly Damages Bones

• Low energy availability (EA) causes bone loss through two independent pathways: hormonal disruption AND direct nutritional effects on bone metabolism 2
• Weight loss medications induce a state of energy deficit that triggers harmful metabolic changes including decreased estradiol, decreased leptin, increased cortisol, and decreased IGF-1—all of which promote bone loss 2
• Even when menstrual cycles appear normal, energy restriction causes measurable bone remodeling changes within just 5 days, with a dose-response relationship between energy deficit and bone damage 2

The Mechanism Is Independent of Your IUD

• Your absent menstrual cycle from the levonorgestrel IUD is not causing low estrogen systemically—the IUD works locally and does not suppress ovarian function in most users 3, 4
• The levonorgestrel IUD does not cause bone loss: studies show BMD remains stable even after 10 years of use, with normal estradiol levels maintained 5
• The bone risk from weight loss medications comes from metabolic energy deficiency, not from menstrual status 2

What Actually Happens With Intentional Weight Loss at Normal BMI

Direct Bone Damage Pathway

• Energy restriction below 30 kcal/kg fat-free mass/day disrupts bone remodeling, causing osteoclast activity (bone breakdown) to exceed osteoblast activity (bone formation) 2
• This occurs even with normal menstrual function present, demonstrating that undernutrition directly damages bone independent of hormonal status 2
• The bone microarchitecture deteriorates with decreased trabecular number, decreased cortical thickness, and ultimately decreased bone strength and increased fracture risk 2

Hormonal Cascade That Worsens Bone Loss

• Weight loss from normal BMI triggers multiple hormonal changes: decreased estradiol, decreased progesterone, increased cortisol, decreased T3, and decreased IGF-1 2
• These hormonal changes occur even before menstrual cycles are affected, meaning you can have bone damage while still having periods (or in your case, while having IUD-related amenorrhea) 2
• The combination of direct nutritional effects plus hormonal disruption creates compounding bone loss 2

Critical Misunderstanding to Correct

Your IUD Is Not the Problem

• The levonorgestrel IUD releases only 20 micrograms of hormone daily into the uterine cavity with minimal systemic absorption 3
• Long-term studies show no BMD loss in levonorgestrel IUD users compared to copper IUD users, even after 10 years of use 5
• Your amenorrhea from the IUD is a local endometrial effect, not a sign of ovarian suppression or low estrogen 3, 4

Weight Loss Medications Create the Real Risk

• Weight loss medications induce the exact metabolic state (low energy availability) that causes bone loss in female athletes and patients with eating disorders 2
• Starting at BMI 23, any further weight loss moves you into the high-risk category where osteoporosis prevalence increases dramatically 1
• The "weight loss shot" effect is fundamentally different from your IUD—it creates systemic energy deficiency that your body interprets as starvation 2

What You Should Do Instead

Maintain Your Current Weight

• A BMI of 23 is healthy and protective against osteoporosis—moving lower increases your fracture risk substantially 1
• Focus on adequate nutrition with energy availability >30 kcal/kg fat-free mass/day to protect bone health 2

Optimize Bone Health at Your Current Weight

• Ensure adequate calcium and vitamin D intake 2
• Engage in regular weight-bearing exercise, which increases bone density when combined with adequate nutrition 2
• Avoid smoking and excessive alcohol, which independently damage bone 2

Consider Bone Density Screening

• Given your concern about osteoporosis risk, discuss baseline DEXA scan with your physician to establish your current bone health status 1
• This provides objective data about whether intervention is needed, rather than pursuing weight loss that will worsen any existing bone concerns 1

The Bottom Line

The combination of weight loss medications with your already-normal BMI creates a perfect storm for osteoporosis development. Your IUD-related amenorrhea is irrelevant to this risk—the danger comes from inducing metabolic energy deficiency in a body that doesn't need to lose weight. Women with low BMI have 1.8 times higher odds of osteoporosis compared to normal BMI women, and each unit of BMI lost increases this risk by 12% 1. Pursuing weight loss from BMI 23 would move you in exactly the wrong direction for bone health, regardless of your menstrual status.