What are yams
Yams are a starchy root vegetable that form the staple of the diets of many in areas of West Africa as well as the Caribbean and Asia due to their good nutritional content and ease of production.1 From having benefits in digestion, antioxidant and cancer-fighting properties as well as being a good source of carbohydrates, including yams in your diet may help you in your weight loss journey. Yam has the characteristic features of a tough outer brown skin with a pale-coloured interior and a taste similar to that of potatoes.1 Yams can be prepared similarly to white potatoes you might be more familiar with by boiling, baking or frying. This makes them a very versatile food option too.
In North America the name “yam” is often used interchangeably to also describe sweet potatoes.2 There are many types of sweet potatoes including purple sweet potato, orange, white cream and yellow. Sweet Potatoes have a characteristically sweeter taste than potatoes and can also be prepared in the same ways e.g. boiled sweet potato, sweet potato mash, sweet potato fries. While Sweet potatoes have many nutritional benefits of their own they are a distinctly different root vegetables from yams. True Yams are of the Dioscoreaceae family of plants while Sweet Potatoes are part of the Convolvulaceae family.1 While they may appear similar and both form edible tubers, they are completely different.
So if you are someone interested in incorporating yams into your diet and you want to find out more about how they can help with weight loss and other health benefits read on below.
Benefits of yams for weight loss
Before explaining the benefits of weight loss we must first explain how weight loss occurs. Each day you eat food which your body digests and turns into sugar glucose which your body then converts into energy. A process called respiration. Your body also extracts nutrients from the foods you eat. Both processes are key in biological processes that keep you alive as well as give you the energy to do literally anything.3 Your body has a requirement for a certain amount of energy (calories) per day to keep all of this going.3 If you were to overeat and eat more calories than your body requires on a regular basis, your body would begin to store that extra energy as fat resulting in weight gain. If you are then eating less you are giving your body fewer calories than your body requires. So your body will begin to use the fat it had stored previously as a source of energy in a process called gluconeogenesis which occurs in the liver.4 The fat is broken down into glucose which is then used to create the energy required by your body. So to lose excess belly fat you would have to put yourself in a calorie deficit which is where you are deliberately eating moderately fewer calories than your body needs. Which makes your body use up the fat stores as energy. This can be quite difficult however there are many features of yams that can help with this.
80% of yams' dry weight comes in the form of starch which makes it an excellent energy source.5 Starchy foods in particular tend to have the combination of very useful nutrients as well as being composed of complex carbs which your body takes longer to digest. This is known as “food having a low glycaemic index”. The benefits of low glycaemic index foods in weight loss is that they raise your blood sugar levels gradually over a prolonged period. This has the benefit of exercise where eating low glycaemic foods as part of a pre-workout meal will give you the energy required to complete your workout to the fullest. This also makes you less hungry as your blood sugars are more likely to remain at a good level for longer giving your body a long-lasting source of energy and making you eat less. This is in comparison to higher glycaemic index foods which are digested and broken down very quickly causing a very sharp rise and fall in blood sugar. This is because high glycaemic index foods tend to be filled with simple carbohydrates rather than complex carbs. This may immediately provide you with a lot of energy very quickly but has the downsides of depleting and crashing your blood sugar levels just as quickly This leads to effects such as making you hungrier, and tired faster both of which lead to overeating
Yams are also filled with dietary fibre which is fantastic for weight loss as foods high in either fibre or protein have been shown to make you feel fuller which prevents overeating.5,6 100 g of yams contains 4.1 grams of fibre which is 13.6% Of the recommended daily dietary fibre intake.7 This is also almost double the fibre of a regular white potato (2.1g) Couple this with yams having an energy content of 118 kcals per 100g in comparison to the potatoes 77kcal per 100g (for reference 100 grams of chocolate contains 546 kcal and has a very high glycaemic index) and it’s easy to see how incorporating this food into your diet can be very effective in controlling your caloric intake.7-9
Other health benefits of yams
There are many other amazing health benefits to eating yams that do not have to do not necessarily have to do with weight loss. Yams are known to contain many antioxidant compounds which have benefits such as: Preventing cancers by preventing the degree of DNA damage that typically leads to regular cells becoming cancerous, triggering the destruction of cells that have already become cancerous, Reducing inflammation, helping with regulating your blood pressure, and strengthening your immune system.5 Their low glycaemic index makes them a very good choice for those with diabetes as this provides greater control over blood sugar levels.10,11 They have a very low-fat content which is good for managing cholesterol levels also which can prevent heart disease.
Yam is an excellent source of potassium which is an important nutrient which has many roles in the body including regulating the volumes of liquid in your body being used to maintain your heart rhythm, nerve transmission and muscular contractions.5 100g of yams contains enough potassium to meet 17% of the recommended dietary intake which is much higher than similar root vegetables and tubers like sweet potato and white potatoes.7,8
Yams are also an excellent source of the B vitamins. There are 2 types: Vitamin B1 (Thiamine) and Vitamin B6.12 Vitamin B1 is important as it forms part of the enzyme pyruvate dehydrogenase which plays an extremely important part in the process of creating energy from the foods you eat. A deficiency in B1 can have very serious consequences particularly in your nervous system. Vitamin B6 is involved in over 100 different reactions in your body which primarily have to do with how your body creates proteins and so it is also a very important nutrient to have. Vitamin B6 deficiency can lead to many problems including anaemia, tongue swelling, confusion and depression. 100g of yams contains 23% of the daily recommended Vitamin B6 content as well as 10% of the recommended Vitamin B1 daily requirements making it a very efficient source7
Vitamin C is also highly present in yams with 100g of yam containing 21% of the daily recommended vitamin C. Vitamin C is commonly found in citrus fruits like oranges, lemons, and limes and is very important for your body’s ability to repair itself. Famously, deficiency in this vitamin C is known to be the cause of scurvy which used to affect pirates. Vitamin A is present, but it is not as prevalent as vitamins B and C with 100g only giving 1% of recommended vitamin A intake. However, it contains significantly more vitamin A than potatoes.7,8
Side effects and other concerns
The yam that is typically eaten is not typically associated with any toxic effects however wild versions such as the species referred to as bitter yams might contain compounds called steroid saponins in large quantities. This typically makes them taste bitter and unpleasant hence the name. At toxic levels, this can lead to symptoms of nausea, confusion and convulsions. However, this is a very minor concern as wild yam is not typically cultivated for food.13
In summary, if you are looking for a nutrientrich source of carbohydrates to help you in your weight loss journey then yams are an excellent source. Their combination of complex carbs and high fibre makes them a great option for weight loss as these features prevent overeating. There are numerous other health benefits that can come from eating yams and so you should consider adding yam to your diet even if weight loss is not your main goal
- Britannica. Yam 2022 [cited 2023 3 January]. Available from: https://www.britannica.com/plant/yam
- Collins-Smith MSM. Sweet Potatoes vs. Yams: What’s the Difference? : Mississipi State University 2019 [updated Nov 2019; cited 2023 3 Jan 2023]. Available from: Sweet Potatoes vs. Yams: What’s the Difference?
- Greenway FL. Physiological adaptations to weight loss and factors favouring weight regain. International journal of obesity (2005). 2015;39(8):1188-96.
- Melkonian EA, Asuka E, Schury MP. Physiology, Gluconeogenesis. StatPearls. Treasure Island (FL): StatPearls Publishing Copyright © 2022, StatPearls Publishing LLC.; 2022.
- Obidiegwu JE, Lyons JB, Chilaka CA. The Dioscorea Genus (Yam)-An Appraisal of Nutritional and Therapeutic Potentials. Foods (Basel, Switzerland). 2020;9(9).
- Salleh SN, Fairus AAH, Zahary MN, Bhaskar Raj N, Mhd Jalil AM. Unravelling the Effects of Soluble Dietary Fibre Supplementation on Energy Intake and Perceived Satiety in Healthy Adults: Evidence from Systematic Review and Meta-Analysis of Randomised-Controlled Trials. Foods (Basel, Switzerland). 2019;8(1).
- AGRICULTURE USDO. Yam, raw 2018 [cited 2023 5 January]. Available from: https://fdc.nal.usda.gov/fdc-app.html#/food-details/170071/nutrients.
- AGRICULTURE USDO. Potatoes, flesh and skin, raw 2023 [cited 2023 5 Jan 2023]. Available from: https://fdc.nal.usda.gov/fdc-app.html#/food-details/170026/nutrients.
- AGRICULTURE USDO. Chocolate, dark, 45- 59% cacao solids 2018 [cited 2023 5 jan]. Available from: https://fdc.nal.usda.gov/fdc-app.html#/food-details/170271/nutrients.
- Ampofo D, Agbenorhevi JK, Firempong CK, Adu-Kwarteng E. Glycemic index of different varieties of yam as influenced by boiling, frying and roasting. Food science & nutrition. 2021;9(2):1106-11.
- Zafar MI, Mills KE, Zheng J, Regmi A, Hu SQ, Gou L, et al. Low-glycemic index diets as an intervention for diabetes: a systematic review and meta-analysis. The American journal of clinical nutrition. 2019;110(4):891-902.
- Hanna M, Jaqua E, Nguyen V, Clay J. B Vitamins: Functions and Uses in Medicine. The Permanente journal. 2022;26(2):89-97.
- Botanical. Yam Toxicity 2021 [cited 2023 3 Jan]. Available from: https://www.botanical-online.com/en/food/yam-toxicity.