Diabetes and your diet: Can intermittent fasting help? What about artificial sweeteners and high-fat food?

In a world where information – and sometimes, misinformation – are served and consumed daily, it can get confusing when you’re trying to eat better for your health. Things are further complicated when you’re also managing a chronic disease such as diabetes.

For instance, you might have heard advice to avoid sweet fruits or only eat certain types of fruits. Well-meaning messages flood your WhatsApp chat group with supplement recommendations to help you keep your blood sugar levels under control.

At home, someone has replaced all the white sugar with coconut sugar or honey because they heard the latter are better for diabetics. Or you might be mulling over this little nugget: Intermittent fasting can help lower blood sugar levels – and help you lose weight as well.

It is a lot of information to sieve through for the over-400,000 Singaporeans who currently live with diabetes. And there will be more joining the ranks. By 2050, that number is projected to exceed 1 million, according to the Ministry of Health.

So, what is, in Gen-Z speak, cap or no cap? We’ve done part of the work for you by speaking to the medical experts themselves: Associate consultant Dr Tan Yu Quan from SingHealth Polyclinics - Bedok, and dietitian Tan Yan Lin from SingHealth Polyclinics. Here are some of the common dietary notions revolving around diabetes you may have come across.

CAN INTERMITTENT FASTING HELP SINCE MANY PEOPLE HAVE LOST WEIGHT USING THIS METHOD?

“Weight loss in overweight and obese people with diabetes is known to improve blood glucose control,” said Yan Lin. But she qualified that the improvement is “more likely due to the weight loss itself” rather than using intermittent fasting. “Compared to traditional dietary advice, intermittent fasting does not show significantly better results,” she said.

“While current research suggests that intermittent fasting might have potential for managing diabetes, the results are not consistent,” said Yan Lin. “Some studies have even found that intermittent fasting does not affect glucose metabolism at all. More studies with larger groups and longer follow-ups are needed to better understand its long-term effects and how sustainable it is.”

The other big thing for diabetics to consider is hypoglycaemia or low blood sugar, which can occur during extended periods of fasting if you’re on certain diabetes medication and/or insulin, cautioned Yan Lin. “Hyperglycaemia or high blood sugar, can also occur if individuals consume an excessive amount of carbohydrates during their eating window” when they fast intermittently.

But the foremost concern is nutrition. “Regardless of what method or diet you follow, it should be balanced and provide all the essential nutrients,” said Yan Lin. “For example, you might risk losing muscle mass if you do not get enough protein or have deficiencies in nutrients like iron or calcium.”

There’s also sustainability or how long you can keep it up. “Finding a weight-loss method that is sustainable and that you can stick to is more important,” said Dr Tan. Yan Lin added that “if intermittent fasting makes you feel lethargic until noon, or it greatly limits your social life and causes unnecessary stress, then it may not be suitable for you”.

In short, consult a dietitian before starting any diet or making dietary changes when you have diabetes.

ARE SOME FRUITS BETTER THAN OTHERS FOR DIABETICS?

When it comes to fruits, you may have been advised by family and friends to avoid mangoes, grapes, bananas and durians as they supposedly contain more sugar. It couldn’t be further from the truth, said Yan Lin. “There is no single best or worst fruit for people with diabetes.”

“While fruits may contain more sugar than other food, that does not mean you are not allowed to eat them if you have diabetes. Eating different fruits can help you to get a better mix of nutrients and phytochemicals,” she said. “Fruits offer different nutrients, so eating a variety is beneficial.”

The key is portion size, she said. “Generally, having two servings of fruit per day is a good guideline.” One serving could be a medium apple, orange or pear, or a wedge of papaya or pineapple, or about eight to 10 grapes.

But don’t diabetics have to avoid food ranked high on the glycaemic index or GI? “The GI measures how quickly a food raises blood sugar levels on a scale from 0 to 100. It does not consider how much of the food you eat,” said Yan Lin.

“In the context of blood glucose levels, the total carbohydrate content will have a larger impact on the blood glucose rather than the GI. Therefore, patients with diabetes can eat different types of fruit as long as they watch their portion sizes,” she said.

FRESHLY SQUEEZED FRUIT JUICES SHOULD BE BETTER THAN THOSE BOTTLED ONES, RIGHT?

“In general, it is recommended for patients with diabetes to consume fresh fruits instead of fruit juices,” said Yan Lin. “Fruit juices can be high in natural sugars and contain less fibre than the whole fruit.”

What’s more, fruit juice is easier to finish than the actual fruit, which can make it easy for you to consume a lot of fruit quickly and cause blood sugar levels to spike, she cautioned. “For example, drinking one cup of orange juice is much faster than eating four whole oranges.”

Speaking of four whole oranges, those vending machines that promise that amount of fruit in each cup of freshly squeezed juice are just too much for diabetics to consume at a go, said Yan Lin. Furthermore, “when oranges are juiced, most of their fibre is removed. Fibre helps to slow down the absorption of sugar in the bloodstream and can help one feel fuller for longer”.

IS IT TRUE THAT HONEY AS WELL AS BROWN, COCONUT AND ARTIFICIAL SUGAR ARE BETTER THAN WHITE SUGAR?

Sorry, but all types of sugar, whether it is white, brown or coconut, have similar effects on your body, said Yan Lin. Ditto for honey. “None are better for diabetes.”

However, when it comes to artificial sweeteners such as stevia, Yan Lin is of the opinion that they are better than white sugar as “they do not raise blood sugar levels and can help with weight management”.

“Studies that suggest sweeteners might have potential negative effects are mostly observational studies, which are not the most reliable for drawing firm conclusions,” she said.

“These studies might show that people using sweeteners are often already obese, which could be why they are at high risk for heart problems, not necessarily because of the sweeteners. Overall, the evidence linking sweeteners to negative effects is considered to be quite low in certainty.”

What about sugar alcohols such as maltitol, sorbitol, xylitol and erythritol? “Sugar alcohol is a type of carbohydrate that is similar to sugar but is not completely absorbed or digested by the body,” Yan Lin explained. “As such, they contain fewer calories (between 0.2 and 2.6 calories per gram) compared to regular sugar, which has 4 calories per gram. They also have a lower GI than regular sugar; hence, they do not raise blood sugar levels as much.”

Still, it’s no excuse to heap on the artificial sweeteners and sugar alcohols. “Most sweeteners do not have health benefits on its own and it is best to consume them in moderation,” said Yan Lin. Sugar alcohols “are not fully digested and can ferment in your gut”, leading to “gas, bloating, abdominal pain and diarrhoea”.

It still pays to reduce your sugar intake if you’re diabetic. Instead of going cold turkey, Yan Lin recommended cutting your usual one teaspoon of sugar in your coffee to half for a week or two, then cut it down again. “Over time, you might find that your coffee tastes sweeter than it used to because your taste buds have changed.”

Or try new flavours. “Many people find that they can enjoy certain teas without sugar, like Japanese green tea, or herbal or floral teas. These types of tea, especially higher qualities ones, often have rich, complex flavours that might make you crave less sugar.”

Drinking fewer cups of sweetened coffee or tea can also help. “Consider switching out one or two cups a day,” said Yan Lin. Or flavour your morning cuppa with a slice of lemon, ginger or even a small amount of milk to make it taste better and reduce the need for sugar, she suggested.

ARE HIGH-FAT FOODS BETTER THAN HIGH-CARB FOODS FOR DIABETICS BECAUSE THEY DON’T RAISE BLOOD SUGAR LEVELS?

Fat seems like a double-edged sword for diabetics. On one hand, they slow down the rise of blood sugar levels. At the same time, fat can also lead to weight gain, which is something many diabetics have to watch.

“As a general guideline, fats should make up about 25 per cent to 30 per cent of your total daily calories,” said Dr Tan.

His tips: Aim for healthy fat sources – cholesterol- and heart disease-reducing monounsaturated and polyunsaturated fats – such as oil from olive, canola, peanut and soybean; most nuts (almonds, cashew nuts and hazelnuts); seeds (sunflower seeds and sesame seeds); and avocados. You can’t go wrong with oily fish such as salmon, sardine and Spanish mackerel either, he said.

“Try to limit saturated fats found in butter, lard, ghee, the fat and skin on meat, palm-based vegetable oil, and the trans fat found in fried food and baked goods, including pastries, cakes, cookies and biscuits,” said Dr Tan.

WHAT ABOUT SUPPLEMENTS? CAN THEY HELP TO CONTROL BLOOD SUGAR LEVELS AND REDUCE THE RELIANCE ON MEDICATION?

You may have heard that bitter melon, fenugreek, ginseng, cinnamon and milk thistle supplements could supposedly help with blood sugar control. The reality is, there is currently “no solid evidence” about how well supplements work for controlling blood sugar, said Dr Tan.

“With the rise in the popularity of wholistic or complementary medicine, many people view ‘natural’ and plant-derived supplements as safer and more in tune with the body than ‘synthetic’ medications, which they believe might have more side effects,” said Dr Tan.

But he advised to “approach these supplements with caution”. “Although some supplements are marketed as safe and effective for lowering blood sugar, they are not as well studied and tightly regulated as pharmaceutical medications,” he said.

“This can lead to differences in quality and possible side effects, especially if purchased from unreliable sources. Before starting any new supplements, it is a good idea to talk to a doctor to make sure they will not interfere with any other medications you are taking,” said Dr Tan.

His advice to diabetics who are keen to try supplements? “It is recommended to use them alongside their prescribed medications as directed by their doctors, rather than relying on them alone. They should also closely monitor their blood sugar levels.”

Even if it's just multivitamins, check whether a diabetic-friendly version is available, Dr Tan added.