Harvard Health Letter

5 mistakes that will sabotage a healthy diet

Excluding the wrong foods and following eating plans that are too restrictive may do more harm than good.

If you’ve ever made a New Year’s promise to eat more healthfully, then you know how easy it is to slip back into less healthy eating routines. “People go into these plans with the best of intentions, but sometimes they don’t have the best information to support their changes,” explains registered dietitian Kathy McManus, director of the Department of Nutrition at Harvard-affiliated Brigham and Women’s Hospital.

Whether you’ve chosen an eating plan to lose weight or to address a health problem (for example, a low-salt diet to help lower your blood pressure), it’s important to understand the little things that can throw you off track.

See if you recognize any of the following common mistakes and consider McManus’ advice to overcome them.

1. Eating a diet that’s too restrictive

It’s hard to stick to diets requiring you to exclude foods in an unrealistic way. For example, if you vow never to eat another sweet again, you may cave in to cravings faster than you would have if you’d allowed yourself a reasonable treat occasionally. “Being restrictive is not sustainable. You have to think about looking at this for the long haul,” McManus says.

She recommends that you make your new eating plan a lifelong commitment. “Make it balanced, so you don’t feel deprived,” she suggests. If you want a treat, consider your daily calorie allowance (it must be tailored to your health and weight), and remember that a small amount of added sugar is acceptable — no more than 24 grams per day for most women, and no more than 36 grams per day for most men, according to the American Heart Association.

2. Excluding the wrong foods

McManus warns about avoiding healthy foods because you assume they’re bad for health. Yes, you should avoid artificial trans fat (which is found in packaged foods, raises “bad” LDL cholesterol and triglycerides, and lowers “good” HDL cholesterol), limit saturated fat (found in foods like butter and red meat), and stay away from processed or packaged foods (which are typically high in salt, sugar, and trans fat). But don’t avoid these:

Healthy fats. After the no-fat eating craze of the ’90s, some people still have a dietary fat phobia. Fats do have more calories per gram compared with carbohydrates and protein, but unsaturated fats are important for cardiovascular health. They’ve been found to lower LDL and total cholesterol when substituted for saturated fats. Include healthy fats in your diet by choosing avocados, olive oil, nuts, nut butters, and seeds.

Fruits. Nature’s sweet treats have sugar, but your body handles it differently than added sugar, thanks to the fiber that’s also in fruit. Don’t forget that fruits are also loaded with vitamins and antioxidants. Berries in particular are associated with less weight gain and a lower risk of having a heart attack.

3. Keeping unhealthy foods within reach

It’s more challenging to avoid unhealthy foods if you stock them in your pantry, even if they are intended only for a special occasion. “The best thing to do is surround yourself with healthy food,” McManus says. “That’s what you’ll eat when you find yourself looking for a snack. But if you buy a half gallon of ice cream, eventually it will go into your stomach.”

Instead, when you want a delicious dessert or something you shouldn’t have every day, go out and get it at that time — not well in advance.

4. Eating at night

Eating at night can lead to trouble. For example, maintaining a habit of eating while you watch TV can lead to overeating. Saving up your daytime calories for a nighttime meal is also unhealthy.

“You need calories during the day, when you’re expending energy,” McManus says. “And if you’re not eating enough in the day, you may be so hungry at night that you overeat.” Plus, eating before bedtime can lead to heartburn, which may keep you from getting a good night’s sleep.

McManus suggests that you rethink the timing of your meals and space out your calories throughout the day. If you’re hungry at night, it may be fine to eat a snack (like fruit or a handful of nuts) if it’s part of a healthy meal plan and fits within your calorie goals.

5. Not keeping track of your food intake

“Research shows that people who track their food intake, if they’re trying to lose weight or monitor sodium in diet, are more successful,” says McManus, “It makes you aware on a regular basis of what you’re putting in your mouth and how much you’re eating.” She also points out that tracking your food provides you with an overall picture, so you can figure out what’s working and what isn’t. “Maybe you’ll see you’re overeating at night because you’re overly hungry,” McManus says.

A way to solve this problem is to keep a food diary. Use a notebook and write down information or use an app (for an electronic gadget), such as My Fitness Pal (www.myfitnesspal.com) or the USDA’s Food Tracker (www.supertracker.usda.gov), which also links you to apps that help you manage weight goals and physical activities.

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