By Bhanvi Satija

June 20 (Reuters) - Treatments designed to help patients

preserve muscle while losing weight with popular obesity drugs

by Eli Lilly ( LLY ) and Novo Nordisk could generate

more than $30 billion in sales by 2035, analysts at TD Cowen

said on Friday.

About a dozen companies are racing to develop such

therapies, most of which are being tested in combination with

Lilly's Zepbound or Novo's Wegovy, both of which target the

GLP-1 protein to help control appetite.

The initial Wall Street estimates for muscle-preserving

therapies follow promising mid-stage results from experimental

drugs developed by Regeneron and Scholar Rock ( SRRK ).

Investors are closely watching mid-stage data from Lilly's

muscle mass-preserving drug, bimagrumab, which is scheduled for

presentation at a medical conference next week.

Analysts have projected that obesity drugs sales could reach

$150 billion a year by the early 2030s. The unmet need to

preserve muscle will grow with the use of GLP-1 drugs for

obesity, said TD Cowen analyst Tyler Van Buren.

Doctors have raised concerns that patients may experience a

decrease in overall strength due to muscle loss associated with

Zepbound and Wegovy, while experts suggest that more muscle can

help patients maintain long-term weight loss.

Van Buren said that the first such treatment could launch by

2028, although regulatory challenges remain because these

treatments must demonstrate additional health benefits to secure

approval.

"We believe quality of weight loss and lean mass

preservation ... is far too important for long-term health

outcomes to be ignored and that this will be figured out," Van

Buren said.

Some of the new drugs target the myostatin protein, which is

associated with muscle growth, and are expected to see broader

use due to their superior safety profile, capturing the majority

of the market share, Van Buren said.

Other drugs target activin, a protein with multiple

biological functions. Van Buren said that activin-based drugs

will be reserved for patients at higher risk of losing strength,

forecasting sales of about $5 billion by 2035.