This is a multicenter, randomized, double-blind, placebo-controlled Phase I study to evaluate safety, PK and PD of single ascending dose (SAD) and multiple ascending dose (MAD) of XTL6001 injection in healthy and obese adult subjects.

SAD study: Includes 5 dose cohorts, with 40 subjects planned for enrollment. MAD study Includes 2 dose cohorts, with 30 subjects planned for enrollment.

Inclusion Criteria:

Inclusion Criteria for Subjects in SAD part:

1. Age ≥ 18 and < 65 years at screening.
2. Body mass index (BMI) ≥ 18.5 kg/m² and < 28.0 kg/m² at screening.
3. Body weight ≥ 50.0 kg for males and ≥ 45.0 kg for females at screening.
4. Signed informed consent form prior to the trial, with full understanding of the study objectives, procedures, and potential adverse reactions.

Inclusion Criteria for Subjects in MAD part:

1. Age ≥ 18 and < 65 years at screening.
2. BMI ≥ 18.5 kg/m2且 < 40.0kg/m².
3. Body weight ≥ 50.0 kg for males and ≥ 45.0 kg for females at screening.
4. Stable body weight (fluctuation < 5%) for at least 3 months prior to screening.
5. Signed informed consent form prior to the trial, with full understanding of the study objectives, procedures, and potential adverse reactions.

Exclusion Criteria:

Exclusion Criteria for Subjects in SAD part:

1. History of type 1 or type 2 diabetes mellitus, or HbA1c > 6.5% or fasting plasma glucose > 7.0 mmol/L at screening.
2. Clinically significant gastric emptying disorders, chronic use of medications directly affecting gastrointestinal motility, severe chronic gastrointestinal diseases, or prior gastrointestinal surgery.
3. History of acute or chronic pancreatitis.
4. Symptomatic gallbladder disease.
5. Malignancy within 5 years prior to screening (except adequately treated non-melanoma skin cancer).
6. Personal/family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2A/2B (MEN 2A/2B).
7. Female subjects with positive pregnancy test or lactation.

Exclusion Criteria for Subjects in MAD part:

1. History of type 1 or type 2 diabetes mellitus, or HbA1c > 6.5% or fasting plasma glucose > 7.0 mmol/L at screening.
2. UnderlyingCushing's syndrome, hypothyroidism, PCOS,.
3. Clinically significant gastric emptying disorders, chronic use of medications directly affecting gastrointestinal motility, severe chronic gastrointestinal diseases, or gastrointestinal surgeries that may compromise safety or data interpretation.
4. History of acute or chronic pancreatitis.
5. Symptomatic gallbladder disease.
6. Malignancy within 5 years prior to screening (except adequately treated non-melanoma skin cancer).
7. Personal/family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2A/2B (MEN 2A/2B).
8. Female subjects with positive pregnancy test or lactation.