What is the most important rule to follow for a healthy diet?
Maintaining enough vitamins, minerals and proteins while limiting calories is by far the most important rule to a healthy diet regardless of their source and whether or not they are "natural" or "whole". Repeated studies have shown that having excess body fat, type 2 diabetes and weight gain are resultant from eating and storing more calories than one burns. Eating too many of any form of calories whether from whole foods or not will cause these problems. A Newcastle University team has recently discovered (2011) that Type 2 diabetes can actually be reversed by an extreme low calorie diet alone.
I should avoid fat, right?
Fat calories are not "worse" than other calories. Fats are essential for many bodily functions including metabolism, brain function, and testosterone production. However, fats are more calorically dense than other macronutrients and provide more calories - this makes a difference if you are attempting to eat at a deficit.
Well then I should avoid sugar because of insulin spikes, right?
Insulin gets a bad rap. Sugar isn't the only thing that spikes insulin - protein does too. Insulin is considered to be the anabolic hormone - you need it to build muscle.
Rather than worrying about insulin, you should worry about whatever diet works the best for you and helps you hit your overall caloric goals.
Which diet plan is the best?
There is no best. There are many paths to maintaining a good diet and losing weight. The important thing to understand is that people are different in their tastes and lifestyles but not in their body metabolisms by any large degree. Resting body metabolism between extreme athletes and unfit people vary by less than 5% which means it has virtually no impact on how much you can eat or burn in daily decisions. You should be prepared to experiment and find what works for you so that you can maintain a diet that avoids an excess of calories over your lifetime however actively you choose to live.
In the end, the "best diet" is the one that you will stick to.
What about Intermittent Fasting?
Intermittent fasting, or IF, has been shown to increase metabolic rate in some circumstances. But at the end of the day, IF is just another way to reduce caloric intake over a 24 hour period. It is merely a "trick" to eat less.
What's the deal with low carb diets?
Low-carb dieting is another "trick" that allows people to stop eating so much sugar and carbohydrates (flours and starches and pastas) which greatly reduces caloric intake without jeopardizing vitamin, protein or essential oils (fats) losses. Most processed carbohydrate sources are not nutrient-dense foods and are not ideal, unless you are trying to store more energy for more significant periods of exertion (e.g. marathon, distance bicycling or days of long hiking).
Carbohydrates are not what makes people fat. Calories matter most. However, low-carb diets have been shown to improve fasting plasma glucose and insulin levels, cholesterol levels, blood triglycerides, preserve muscle mass during weight loss, and other health markers.
Low-carb dieting has side benefits for ultra-endurance athletes (increase in intramuscular triglycerides), but can negatively impact high intensity strength training by reducing muscle glycogen and forcing the body to convert protein into glucose, rather than use it for muscle building.
What about Paleo / Primal / Keto / South Beach / Atkins ?
These are restrictive diets that also use "tricks" to make people simply eat less calories. The tricks vary, but usually result in a person eating a low-carb / high-fat diet, but restricting food choices.
Because food choices are restricted on these diets, finding good things to eat can be tough. Below is a list of cookbooks and websites with information pertaining to these diets:
- Mark Sisson at Mark's Daily Apple has a bunch of good "primal" recipes
- Mark has a cookbook out that has a lot of good "primal" recipes, too, with pictures and so on.
- Joyful Abode's recipe index has a lot of good low-carb recipes in it.
- Everyday Paleo has nice looking paleo recipes
- What does r/Fitness eat for lunch at work?
- r/Paleo and the r/Paleo FAQ
- r/keto and the r/keto FAQ
Can I still get strong if I am a Vegetarian / Vegan?
Yes. Protein requirements vary, but you will probably want to consume a protein supplement in addition to your normal diet if you are strength training. Rice protein, hemp protein, and gemma pea protein are good options, as is soy. Egg or whey protein is ideal if that is allowed.
There are certain important factors to keep in mind when considering vegetable protein. PDCAAS, the FAO/WHO standard for determining protein quality, considers soy protein to be just as useful as whey or animal protein. Unfortunately, recent research suggests that measurements such as BV and PDCAAS do not take into account important factors such as anti-nutritional factors and chymotrypsin inhibitors. These anti-nutritional factors limit the extent to which your body can utilize the protein and are commonly found in soy and other vegetable protein isolates. Thus, it is important to keep in mind that you may require a higher dosage of vegetable protein to gain the same effect.
If you aim for a more moderate but still adequate protein intake (1-1.2g/kg bodyweight or lean mass), then you can achieve this through a healthy and smart diet. Just be aware to eat varied sources for a more complete distribution of amino acids.
Won't soy protein affect my testosterone levels?
In regards to soy usage and phytoestrogens (isoflavones), they do not affect testosterone levels per se. They may modulate the androgen receptor, which mediates the effects of testosterone. This is a 'leveling mountains and filling valleys' effect, and could potentially reduce testosterone if your testosterone levels were well above baseline to start. There is evidence that these same phytoestrogens can actually actandrogenic (like testosterone) in older men suffering from low testosterone!
A conclusive statement about whether soy is 'good' or 'bad' cannot be made about the isoflavone content. Just be aware to cook your soy to denature the trypsin inhibitors so you can actually get the protein. A good review of soy can be found here
Should I take a multivitamin?
If your diet is lacking in vitamins and minerals, a multivitamin might be beneficial, but it is certainly not needed.
Multivitamins are a stop-gap to fill holes in an insufficient diet. The best option is still to get these vitamins from whole food sources when possible.
Should I take other supplements?
As the name implies, supplementation should only be used for additive effects - your primary fitness goals will be mostly achieved via diet and exercise. Still, with that in mind, there are three supplements that are frequently cited for general health and building muscle:
- Omega-3 Supplement such as Fish Oil (note that flax/chia seeds are not sufficient)
- Vitamin D
- Creatine
