Weight loss question about gastric sleeve: 5'7, 300lbs, male late 30s. (Photo)

Congratulations on being proactive in considering your options to make long-lasting improvements in your health and fitness.
Your BMI is 47, meaning you have Class 3 obesity (BMI>40), also known as "extreme" or "severe" obesity. Obesity puts you at risk for obesity-related co-morbidities such as type II diabetes (T2DM), hypertension, sleep apnea and other respiratory disorders, non-alcoholic fatty liver disease, osteoarthritis, lipid abnormalities, gastrointestinal disorders, and heart disease. Thus you are wise to be concerned about your weight, its impact on your health, and the increased difficulty to lose weight or undergo surgery as you grow older.
To qualify for weight loss surgery, the American Society for Metabolic and Bariatric Surgery recommends you meet one of the following:
BMI ≥ 40, or more than 100 pounds overweight.BMI ≥35 and at least one or more obesity-related co-morbidities such as type II diabetes (T2DM), hypertension, sleep apnea and other respiratory disorders, non-alcoholic fatty liver disease, osteoarthritis, lipid abnormalities, gastrointestinal disorders, or heart disease.Inability to achieve a healthy weight loss sustained for a period of time with prior weight loss efforts.
From the information you share, you meet the first and third qualifications. I have treated patients with similar dieting results as you, and their weight loss trajectory tends to be similar to other patients. The commitment you are able to maintain in order to lose 30 pounds without surgery suggests you do well with the post-surgery diet after the gastric sleeve.
Meeting with a bariatric surgeon in your area will allow you to further discuss the pros and cons of surgery as well as insurance coverage and the cost for the surgery in your geographic area. You can also check out the Patient Learning Center of the American Society of Metabolic and Bariatric Surgery to educate yourself on surgical options.

Your weight loss experience after gastric sleeve surgery will likely be different from what you've seen with traditional dieting. Since you already lose weight very quickly when you diet, it's likely that you’ll see a rapid drop in the first few weeks post-op, similar to what others experience. Most people lose around 25-30 pounds in the first month, but since you already respond aggressively to calorie restriction, you could lose at the higher end of that range or even exceed it.
The difference with the sleeve is that while dieting on your own leads to extreme water weight loss followed by hunger-driven stalls, the surgery changes the way your body processes food and controls hunger. The removal of most of the stomach significantly reduces ghrelin, the hormone responsible for hunger, which makes long-term weight loss more manageable. Instead of your appetite surging back and causing you to regain, you'll likely find it much easier to stay on track. Even when weight loss slows after the first few months, your smaller stomach and hormonal changes will keep you from feeling as ravenous as you did in the past.
Given that you have decent muscle mass, your body may hold onto weight differently than someone with less muscle, but you’ll still experience a steady drop as long as you stick to the post-op diet and stay active. The biggest change will be that this isn’t just another extreme diet—it’s a metabolic reset that prevents the cycle of losing and regaining due to hunger. If your past weight loss always stalled due to overwhelming hunger, the sleeve will help break that pattern and allow you to sustain your progress long-term.

Hello,First of all, congratulations for taking the time to investigate the best options to improve your health status, with the info that you wrote i know that you are candidate to bariatric surgery. The type of surgery will depend of your evaluation and surgeon criteria before determining which procedure is right for you, you should proceed to an evaluation by a qualified bariatric surgeon. This according to the assessments that will make you determine if the procedure selected is suitable for you.Today we know that in your body the hungry feeling, the fat formation and appetite aren't regulate just by your mind. There are  substances that regulates them, and are high in the obese patient and is more than studied that failure in weight loss are more than 90 % with diet and exercise routines.Today bariatric surgery is the most successful way to lose and maintain the weight, it is safe with low rate of complication and mortality as low as 0.01 percent.My Best Wishes,