When you’re looking for weight-loss advice, there are a lot of vitamin supplements that sound like they might do the trick to help you slim down. So is there anything to the idea that supplements can help a person shed pounds?
“When it comes to weight loss, it’s natural to look for shortcuts, but it’s easy to be misled,” says Karen Ansel, R.D.N., nutritionist and author of Healing Superfoods for Anti-Aging. “Even though there’s a lot of hype online that vitamins or supplements that can help, the truth is eating a healthy, portion-controlled diet is the only proven way to slim down. And vitamin supplements may even backfire by lulling you into complacency about your diet.”
Weight experts frequently get asked what supplements will help, says Jamy Ard, M.D., a clinical researcher focused on treating obesity in adults and co-director of the Wake Forest Baptist Health Weight Management Center. “However, we generally discourage people from trying to over-supplement any mineral or vitamin in hopes of improving their weight loss result, because there is no research evidence to support this notion.”
It helps to remember, Dr. Ard says, that supplements are intended to make up for nutrients that can’t be adequately provided by a healthy diet or due to medical issues that affect absorption of nutrients from food. “If excess weight were caused by a deficiency of some mineral or vitamins, then supplementation would be the answer—however, that is not the case,” Dr. Ard says.
So, what is known about the impact of vitamins on weight loss? We dug into the science and consulted experts to give you the skinny:
There are many, many good health reasons to make sure you’re getting enough fiber in your diet; it’s good for your heart, your blood sugar, and for maintaining a weight that’s healthy for your particular body. Most Americans don’t get nearly enough fiber in the foods they eat, so it’s important to make sure you’re prioritizing fruits and veggies, nuts, beans, and whole grains—especially since it’s much better to get fiber from what you eat than from supplements, because these foods have a host of health benefits that go beyond what a supplement can give you.
“Fiber definitely plays a role in weight loss, but not the kind in supplements,” says Ansel. “Fiber-filled foods help with weight loss in several ways, one of which is slowing you down. High fiber foods like whole grain bread, fruits, and vegetables take time to chew so they automatically make you eat more mindfully. In addition, fiber helps us grow more good gut bacteria, which can help send fullness signals from the stomach to the brain. However, we need lots of different kinds of from many different types of foods to reap this benefit.”
There have been studies on one particular type of natural fiber complex, called Litramine, that has been shown in supplements to potentially help those who are overweight or obese shed pounds. And notably, the research subjects didn’t have the sort of GI distress that some weight-loss meds have caused. Follow-up studies are needed to see if the weight loss can be maintained.
Green tea supplements
Much has been written about the various health benefits of green tea, and there have been reports that when taken in supplement form, green tea can help with weight loss. But a study review done in 2012 showed that taking green tea preparations resulted in just a small amount of pounds lost that was statistically insignificant and “not likely to be clinically important,” according to the study authors. Fortunately, since there are only mild side effects to green tea, it’s not going to hurt—but it shouldn’t be counted on as a way to slim down for your health.
“There is no real benefit for body weight when it comes to use of green tea,” says Dr. Ard. “The other concern I have about the green tea hype is that people start drinking sweetened green tea products and get a lot of added sugar and calories, all the while thinking that this is helpful for weight loss when that's exactly the opposite.”
Vitamin D + calcium
You might have read online about the weight loss powers of a combo of vitamin D and calcium supplements. In fact, research published in 2012 in the American Journal of Clinical Nutrition was undertaken to test that theory. In the study, 171 participants, mainly white men and women, were split into two groups; each day, half of them drank three glasses of OJ fortified with D and calcium. After 16 weeks, that group didn’t lose any more weight (an average of less than 3 pounds) than the other group. However, the fortified-OJ-swigging group lost more visceral belly fat during those weeks. This type of fat sits deep in the abdomen, surrounding other organs, and raises one’s risk of cardiovascular problems. So even though vitamin D + calcium isn’t a magic weight-loss bullet, at least according to this one study, it might be healthy to make sure your diet includes enough of those nutrients, or to talk to your doctor about taking supplements, if you’re interested in that route.
Two older studies (both from 2008) are also worth noting: One suggested that calcium may suppress hunger, and the other (which focused on overweight and obese women) found that the subjects were able to lose more weight on a very low-calorie diet when they had a higher baseline of vitamin D in their bodies. Note, however, that these are old studies, and that restricted-calorie diets are not consider healthy or effective by health experts. Says Dr. Ard, "We know many people with obesity also have low vitamin D levels and correcting that is important for good musculoskeletal health. However, there is no evidence that this will enhance weight loss."
Adds Ansel, “While calcium supplements may not help you lose weight, eating three servings of low fat dairy could provide a slight edge. In addition to being an excellent source of calcium, dairy contains protein, which is slowly digested so it helps you feel full after you eat it. Plus, it has a high water content, which has also been shown to help with appetite control.”
Vitamin B supplements
The various B vitamins (and there are many of them) are said to help boost your metabolism, and thus potentially could help you slim down. In fact, some weight-loss clinics apparently offer B-12 shots to help you shed pounds, by revving up your energy and your metabolism—but according to the Mayo Clinic, unless you have an actual B-12 deficiency, you’re unlikely to get an infusion of energy from these injections. “Theoretically being deficient in B-vitamins could slow your metabolism, but that doesn’t mean popping more of them will speed things up,” says Ansel. “Plus, with the exception of vitamin B12 —which can be an issue for older folks and those on antacid therapy for GERD—very few of us are B-vitamin deficient.”
Says Dr. Ard: “There is no clinical trial evidence that B12 injections work for weight loss. Water soluble vitamins like B12 that are over-supplemented simply get excreted in the urine. So unless you are deficient in B12—which can be assessed with a simple lab test— you’re simply recycling the B12 injection into the toilet. What we see often is that these types of injections are combined with extremely low calorie diets and HCG injections. I don’t doubt that there is some placebo type effect with the commitment required to sustain regular injections, but there is no biological basis for this to work for weight loss.”
As for B vitamins in general: A 2018 study on rats, done in China, found that when the rodents were fed a high-fat diet, giving them B vitamins reduced the amount of weight they gained. However, remember: These were rats (and not that many of them!), and even the researchers said this could only possibly provide the same benefit to humans.
There doesn’t seem to be research linking taking magnesium supplements with weight loss, though you may see that claim made online. A 2013 study done in Newfoundland did find that the women who had the “highest level of adiposity” (translation: who were the most overweight/obese) had the lowest level of magnesium intake. Again, that doesn’t mean that taking magnesium supplements will help you lose weight.
One thing that magnesium may help with, according to some experts: getting a better night’s sleep. Because it has a role in muscle relaxation and nerve function, some sleep doctors recommend magnesium supplements to their patients to help them doze more soundly. And there’s plenty of research linking lack of regular sleep to weight gain. Since magnesium is an important nutrient for your health in general, it makes sense to get plenty of it in your diet: You’ll find it in green leafy vegetables, nuts, and seeds.
The bottom line about vitamins and weight loss
The biggest nutrient gaps in our diet are calcium, vitamin D, potassium, and fiber, says Ansel. “With the exception of vitamin D, all of these are easy to obtain from a healthy diet. When you get these from minimally processed whole foods you’re much more likely to feel naturally full, and you’ll nourish your body with lots of other important nutrients in the process.”
Taking vitamin supplements will not magically help you shed pounds. There are nutrients that may make it more likely that you’ll stick to healthy eating by, say, lifting your mood or revving you up—though there’s no proof that being in a better mood or having more energy is going to help any particular person choose a veggie-centric snack over a bag of chips. Best advice? Cram your meals and snacks full of the healthiest food possible (you know the drill: more produce, lean protein, nuts and seeds, and whole grains, and less sugar and refined foods), because overall, it’s better for your health, from head to toe. Combine that with movement throughout the day—movement that’s fun for you so you’ll stick to it rather than dread it—and getting a decent night’s sleep on a regular basis. And most of all: Love your body for all it can do for you, every day.