What a loaded question!
When people ask me this question I ask them what they are hoping to achieve because there are a few reasons you DO NOT want to use supplements:
Reason #1: A fast weight drop. Sustainable weight loss comes from a combination of an exercise plan and nutrition plan consistently over time. If you use a supplement to drop weight quickly you are very likely to put the weight back on when you come off the supplement because you have not fixed the actual barriers to weight loss.
Reason #2: As a substitute for real food. Your body prefers its nutrients from actual food, in fact it breaks down, digests and then utilizes actual food better than food substitutes like protein bars and pills. There is a saying that you cannot out-supplement a bad diet so get your nutrition in check.
Reason #3: As a substitute for real workouts. There are no short cuts in life. You either do the work or you do not. A supplement may get you to a place faster athletically, but it cannot take the place of good old fashioned hard work. That being said, if your exercise and workout program is not progressing your goals please research if there is a better alternative for you, your body type and your goals. There are options out there you can shift to and try (they all require work though).
There are some really GOOD reasons to take supplements. The best reason is because you and your health practitioner have identified a vitamin or mineral deficiency that you are trying to correct and you are unable to correct it using food. For example, some people have a genetic mutation that affects how they absorb certain B vitamins, so some folks need to supplement with a certain type of Vitamin B.
Another reason is that on your journey to a sustainable and healthier lifestyle, you have recognized you have work to do and want to give your body a head start in the nutrient category until you can get the rest of your lifestyle where it needs to be. For example, if your diet is solely chicken nuggets and French fries, (aka deficient in vitamins, nutrients or protein) and you are working to correct this, supplemental vitamins or protein shakes can really help your body feel and perform better while you are on your way to change!
Supplements can also help boost your immune system. Some great supplements for this time of year when it’s cold, it’s flu season, there are other bugs in the air and we get decreased sunshine and time outside: A quality multi vitamin, Magnesium, Vitamin D, Fish Oil or Omega (3 and 6), zinc, Vitamin C.
I want to wrap up by being clear, though, I am not a physician and any decisions to use supplements and other over the counter medications should be discussed with your physician. But I will warn you that many physicians can be skeptical about supplements so do your own research so you can have educated and informed conversations with your practitioners.